CHIN's

When an ecstasy cook-turned-chemistry-teacher is found murdered in a cozy Los Angeles suburb, Lucifer and Pierce must go undercover to help track down the killer. Meanwhile, Maze has a newfound attraction for someone that she used to despise and Charlotte has a revelation.

After Lt. Pierce's true identity is revealed, Lucifer tries to figure out his motives. In order to earn Chloe's assistance in his investigation of Pierce, Lucifer goes above and beyond to help her solve the murder of a professional surfer. Meanwhile, Amenadiel deals with a personal health issue.

In a flashback episode that takes place when Lucifer first came to LA, Amenadiel comes to retrieve his fallen brother, but is shocked when he is mugged. Amenadiel enlists Lucifer's help to track down the mugger and Lucifer, in turn, offers his assistance – but only in exchange for a favor. Meanwhile, Chloe and Dan – who are still married – investigate the murder of an MMA fighter, Aidan Scott, at the hands of the same killer who mugged Amenadiel.

With the Sinnerman in custody, Lucifer is prepared to go to any length to get his devil face back. Meanwhile, Trixie is introduced to Charlotte and questions the relationship she has with her father.

Lucifer is worried when he realizes that recipients of his favors start to turn up dead. After he and Chloe investigate, they are finally brought face-to-face with the Sinnerman. Meanwhile, Detective Pierce returns to work after taking a bullet, Charlotte finds a new career and Amenadiel has a new love interest.

When a murder is connected to a celebrity dating app, Lucifer and Chloe question all they know about the world of social media in order to solve the case. Meanwhile, Ella tries to avoid Charlotte, and Amenadiel helps Linda deal with the death of her ex-husband.

A reporter seeks revenge when he discovers Lucifer has been sleeping with his estranged wife; a serial killer from Lucifer's past resurfaces.

When Lucifer discovers Candy has gone missing, he hightails it to Las Vegas with Ella in tow. They work to find her, but interesting secrets could compromise the investigation. Meanwhile, Chloe is upset that Lucifer left on her birthday.

When a food chemist is found dead, Lucifer and Chloe's investigation pits them against an unexpected face – criminal defense attorney Charlotte Richards. Everyone is caught off guard when they see her back in the precinct. As Lucifer tries to understand her return, he makes a shocking discovery that helps solve the case.

When a youth counselor is found murdered, Lucifer and Chloe venture into the world of high-end reform programs to find the killer. Meanwhile, Amenadiel adjusts his lifestyle in an attempt to help Lucifer, and Chloe questions Lt. Pierce's feelings towards her.