Blitzo (pronounced "Blitz") (voiced by Rogers), an imp, leads an assassination company in Hell alongside his team: his adopted hellhound daughter Loona (voiced by Erica Lindbeck) and a married couple, Moxxie (voiced by Richard Steven Horvitz) and Millie (voiced by Lindbeck). They cater to clients from Hell seeking murders on Earth, strategizing ways to expand their clientele while reflecting on past missions. A mishap occurs when Moxxie mistakenly targets a young boy, injuring him, which prompts a heated debate among the group. Issues within the company surface, including Loona's detachment from her job and Blitzo's stalking of Moxxie and Millie outside work. Additionally, their portal to Earth stems from a grimoire stolen from Stolas (voiced by Brock Baker), a demon, after Blitzo's brief affair with him. The episode concludes with Loona confirming the boy as the correct target after all, which leads Blitzo to shoot him. Despite their differences, the team reconciles while disposing of the body.

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Musical numbers : "I.M.P Jingle" and "Oh Millie" (end credits)
Note : As of November 2023, the pilot is no longer "functionally canon" to the rest of the series.^[14]

Mrs. Mayberry, a schoolteacher, discovers her husband's infidelity during a video call set up by her students. In a fit of rage, she fatally shoots her husband and his mistress, Martha, before turning the gun on herself, all of which is witnessed by her horrified students via the still-active video call. Now a demon in Hell, Mrs. Mayberry seeks revenge on Martha, who survived the attack and gained money and sympathy through it. She hires I.M.P to kill Martha. Using the grimoire, they travel to Martha's home, where they accidentally alert Martha to their presence. Martha's family is revealed to be devil-worshipping cannibals, who capture Moxxie and Millie while Blitzo narrowly escapes. With help from Moxxie, Martha is killed, but Moxxie is haunted by guilt over the rest of the family's subsequent demise. Upon returning to Hell, Mrs. Mayberry and the team celebrate the job's completion, but Moxxie is left traumatized by the unintended consequences of his actions.

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Musical numbers : "Teacher's Song"

In a flashback scene, a young Octavia is comforted by her father Stolas after a nightmare. In the present day, 17-year-old Octavia witnesses her parents' turbulent divorce sparked by her father's affair with Blitzo. Despite Octavia's reluctance, Stolas insists on taking her to an amusement park called Loo Loo Land, hiring I.M.P as bodyguards to accompany them. At the park, Stolas constantly flirts with Blitzo, making Octavia uncomfortable. During an emotional outburst, Octavia flees, prompting Stolas to pursue her. Meanwhile, Blitzo confronts an animatronic foe and former coworker, Robo Fizz. In a funhouse, Stolas and Octavia discuss their strained family dynamic. Octavia fears abandonment by Stolas, who reassures her of his commitment and apologizes for neglecting her. They depart from the park with the rest of I.M.P, as it burns to the ground as a result of Blitzo's fight with Robo Fizz.

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Musical numbers : "You Will Be Okay" and "Loo Loo Land"

I.M.P's company parking space is stolen by Blitzo's ex, Verosika Mayday, and several of her succubi friends. He challenges her for ownership of the parking space, and the two groups go to Earth in order to compete.

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Musical numbers : "Vacay to Bonetown" and "Mustang Dong" (end credits)

A former inventor who has just entered Hell hires I.M.P to kill his business partner, Lyle Lipton. Before they can, three cherubs from Heaven arrive and try to convince Lipton his life is worth living. I.M.P and the cherubs battle over Lipton's life before the cherubs accidentally kill him, completing I.M.P's job for them. I.M.P returns to Hell, while the cherubs are banned from reentering Heaven.

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Musical numbers : "C.H.E.R.U.B Jingle"

I.M.P visits Millie's parents in the Wrath ring during the Harvest Moon Festival. Their farmhand, Striker, is revealed to be an assassin plotting to kill Stolas. He fails to do so, and informs his client: Stolas' wife, Stella.

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Musical numbers : "Striker's Song"

While on a mission, Blitzo and Moxxie are captured by secret agents. They are interrogated in a facility, where they confess their emotional issues with one another under the influence of a truth serum. Millie and Loona rescue them, but the four are cornered. The group is ultimately saved by Stolas, who possesses an agent and opens a portal to Hell for I.M.P to escape through. However, the facility recorded everything that happened on security cameras, and they hint that the world will soon know that demons exist.

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Musical numbers : "Moxxie's Bad Trip"

Moxxie and Millie go to a couples-only restaurant for their anniversary. Blitzo follows them into the restaurant, taking Stolas with him in order to get in. Stolas is spotted with Blitzo, and the two are humiliated by the restaurant's owner and head entertainer, Asmodeus and Fizzarolli.

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Musical numbers : "House of Asmodeus"

Loona is invited to a hellhound party in the Gluttony ring by Vortex, Verosika's hellhound bodyguard, and meets his girlfriend, the Queen of Gluttony, Queen Beelzebub. Meanwhile, Blitzo processes his feelings after being humiliated at Ozzie’s.

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Musical numbers : "Cotton Candy" and "Monster's Ball" (end credits)

On his birthday, a young Prince Stolas receives a grimoire from his father, Paimon. However, Stolas becomes distraught when Paimon tells Stolas of his arranged marriage to Princess Stella. To cheer him up, Paimon brings Stolas to an imp-run travelling circus. Stolas becomes interested in the young Blitzo, who performs in the circus. After the circus, Paimon arranges with the owner of the circus, Blitzo's father Cash Buckzo, for Blitzo to be Stolas' playmate for a day. Cash Buckzo agrees and secretly instructs Blitzo to steal valuables from the palace. Despite Blitzo's attempts at theft, the two become friends. Twenty-five years later, Stolas is unhappily married to Stella. At their wedding anniversary party, guards brings Blitzo to Stolas after catching Blitzo attempting to break into the palace. Stolas, incorrectly assuming Blitzo is seeking a sexual encounter, propositions him in his chamber, and the two have sex. The next day, Stolas awakens to a half-naked Blitzo falling from the balcony, grimoire in hand, into Stella's garden party. Stella becomes enraged, and Stolas demands a divorce. In the present day, the morning after his disastrous date with Blitzo in "Ozzie's", Stolas reflects on his and Blitzo's relationship. Stella interrupts Stolas and accuses him of betraying her. Stolas contends that their marriage was never based on real love. Stella vows revenge against Stolas for leaving her.

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Musical numbers : "Stolas Sings"^[18][19][20]

Stolas forgets about a meteor shower he had promised to take Octavia to see when she was young. Upset, Octavia steals his grimoire and transports to Los Angeles. I.M.P. and Stolas try to find her. At the Griffith Observatory, Loona has a heart to heart with Octavia, and convinces her that her dad truly loves her. With that, they reunite with their fathers, where Stolas apologizes for forgetting about the meteor shower.

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Musical numbers : "I Like It" and "Til the Day We Die" (end credits)

I.M.P visits Moxxie's father, Crimson, a high-profile mafia crime boss. Crimson tries to force Moxxie to marry Chaz, a shark demon whom both Moxxie and Millie previously dated. I.M.P escapes from Crimson and his men, revealing Chaz's plan to marry into the family so he could steal their money. After killing Chaz, Crimson seeks revenge another day.

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Musical numbers : "Chaz Time", "Crashin' A Wedding"

Striker kidnaps Stolas and intends to kill him under Stella's orders, but her brother Andrealphus informs her that if he does die, his power will go to their daughter, leaving Stella with nothing. She orders Striker to spare him. Striker fights I.M.P, but escapes them, leaving Stolas alive but severely injured.

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Musical numbers : "The Ballad of Striker", "Whatcha Thinkin' About"

Moxxie leads a mission for I.M.P for the first time, and it does not go as planned. Meanwhile, Blitzo searches for his sister, Barbie Wire, whom he wants to reconcile his relationship with. However, Barbie Wire refuses to forgive him.

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Musical numbers : "Regular Joe", "Everybody Look At Me" and "You Got The Power"

Blitzo and Fizzarolli are kidnapped by Crimson and Striker, who demand a large ransom from Asmodeus in exchange for Fizzarolli's release. With no one else coming to their rescue, Blitzo and Fizzarolli have to work together to save themselves, reconciling their past friendship in the process. Meanwhile, Stolas visits Asmodeus to request a crystal that would allow Blitzo to freely traverse between Hell and Earth.

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Musical number : "Look at This"

Fizzarolli competes in a clown pageant held by Mammon, the Prince of Greed, much to Asmodeus’ dismay. Blitzo, brought in to serve as Fizzarolli's bodyguard, also tries to convince his friend to cut ties with Mammon.

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Musical numbers : "Juggling iz Cool," "Klown Bitch," "Crooked," and "2 Minutes Notice"

Blitzo prepares for his monthly night with Stolas. Meanwhile, C.H.E.R.U.B and D.H.O.R.K.S team up to hunt him down, but are stopped by Moxxie, Millie, and Loona. They engage in a fierce battle, but in the end, the cherubs are defeated and sent back to Earth. Blitzo meets with Stolas, only to be informed that their deal is over. Angered and betrayed, he insults Stolas, leaving the latter heartbroken.

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Musical number : "When I See Him"

After another argument with Stolas, Blitzo embarks on an "apology tour", giving half-baked apologies to people he has wronged in the past. The tour culminates on Earth, where Verosika is hosting a Halloween party dedicated to slamming Blitzo for his past actions. Stolas is invited to the party and sings a musical number about still loving Blitzo despite how the latter has treated him, which a disguised Blitzo witnesses. Blitzo begins to realize how terrible he has been and extends genuine apologies to both Stolas and Verosika before leaving the party in shame.

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Musical numbers : "All 2 U (Motherfucker)", "Handle Me", and "Over You"

After his breakup with Stolas, Blitzo blows the company's entire budget as he copes with his grief. I.M.P is hired to kill a target at a haunted hotel, where Blitzo attempts to reenact a television show about a ghost hunter who sleeps with ghosts. Millie eventually tires of Blitzo's antics and they separate, leading to Blitzo being haunted by the demon who killed their client. Blitzo is tormented with thoughts of the people he hurt in the past, and Millie finds him an emotional wreck. Millie has a heart-to-heart talk with Blitzo over the first time they met, and formed I.M.P with Moxxie and Loona, convincing him that he helped make her life better. The two then discover that the hotel's host, Rolando, is a demon from the Envy ring and is the one responsible for killing their client. Rolando possesses Blitzo and continues tormenting him, until Millie beats up Blitzo and forces Rolando out of his body. Blitzo kills Rolando, and he and Millie return home.

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Musical numbers : "A Spooky Kind of Love" and "I Wanna Fuck a Ghost" (end credits)

Andrealphus is informed of Stolas and Blitzo's prior deal by Stella. I.M.P is subsequently arrested and tried in a court presided over by Satan, the Sin of Wrath. Also in attendance are the rest of the Seven Deadly Sins (excluding Lucifer) and the Ars Goetia, including Andrealphus and Vassago. Despite Asmodeus, Bee-lzebub, and Vassago speaking in support of I.M.P and Stolas, Andrealphus attempts to have Blitzo executed by painting him as the aggressor in his deal with Stolas and accusing him of hiring Striker to assassinate him. Satan prepares to televise Blitzo's execution, attracting the attention of Stolas, who intervenes to save Blitzo by taking full responsibility for their deal. Satan spares Blitzo and punishes Stolas by stripping him of his power and status for a hundred years; Andrealphus slyly persuades Satan to let him take Stolas' place. With the entire affair being broadcast, Blitzo and I.M.P become celebrities among their fellow imps after surviving and standing up for all imps, while Stolas is ostracized. Blitzo and Loona take Stolas in for the time being.

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Musical number : "Mastermind"

On Sinsmas, Blitzo, in an attempt to cheer up Stolas, tries to recruit him as I.M.P's new receptionist. Stolas tries to reinstate contact with Octavia, but cannot reach her. I.M.P is hired to kill a client's ex-husband, who started a new life with his lover and their daughters, but Blitzo feels uncomfortable upon seeing the family celebrate Christmas together and cancels the hit. Meanwhile, Octavia discovers Stolas' secret stash of antidepressants, leading her to assume her father was feeling unhappy around her. When Stolas tries to visit her, he is stopped by Andrealphus and the two get into a fight, and I.M.P comes to Stolas' rescue. Octavia breaks up the fight, not wishing to see Stolas be hurt, but renounces her father for choosing Blitzo over his family. As I.M.P celebrates Sinsmas later that night, Millie discovers she is pregnant but decides to conceal this fact from Moxxie; meanwhile, Blitzo and Stolas bond over both their families having rejected them.

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Musical numbers : "Merry Sinsmas", "Day By Day", "I Will Be Okay", "A Sinsmas Party (I'll Murder You)", and "Rage of the Frost Marquis"

Moxxie sings a love song for Millie. The song was previously featured in the pilot for the series.

Set between "Oops" and "The Full Moon", Stolas considers the choice to give Blitzo the Asmodean Crystal and reflects on their relationship up to this point.

Millie spends the day in Imp City with her transgender sister, Sallie May, and both sisters reflect on how their individual jobs affected them both.

A simple assassination trip to Antarctica turns into a narrow escape when Blitzo, Moxxie and Millie flee for their lives from an army of flesh-eating penguins.

Blitzo travels to the human world to assassinate a young woman, only to discover the woman is attracted to demons. He successfully assassinates her, but she then enters Hell as a demon and finds him, vowing to be by his side forever, much to Blitzo's dismay.

Blitzo is captured on a mission gone wrong by a Mexican goat farmer, who passes Blitzo off as the mythical monster, the Chupacabra. Blitzo has to improvise a way to escape and retrieve his gear, when Agents One and Two arrive in the hopes of capturing him as well.