Lucifer and Chloe are tasked with solving the murder of a prominent restaurateur. When they meet his son, they suspect he played a part in the death. Meanwhile, Chloe's mom returns home, sending Chloe's life into upheaval, as Lucifer learns his own dysfunctional family isn't nearly as unique as he thought.
Lucifer and Chloe investigate a gruesome murder after a video of the crime surfaces on social media. When a second video appears, they realize they have a serial killer on their hands. Meanwhile, Lucifer’s mom returns as Charlotte Richards. Also, Amenadiel, struggling with his loss of power, has an appointment with Linda.
Lucifer is excited to investigate the murder of his favorite action movie hero, Wesley Cabot. Longtime rival Rolf Van Zandt initially is a suspect, but the investigation soon shifts. Meanwhile, Uriel shows up and Amenadiel is forced to come clean about his lost powers. Also, Lucifer and Uriel fight about Chloe and their mother.
Following the murder of the owner of the building in which Lux is located, Lucifer and Chloe search for the killer, while Lucifer also deals with the fact that the new owner wants to evict him and demolish the place. Lucifer goes to great lengths to protect his home, and is entirely shocked when Chloe is supportive of him. Meanwhile, Maze and Amenadiel follow Charlotte around, as she comes up with a plan to upset Lucifer enough to want to leave earth and go back to Heaven.
After Lucifer and Chloe have an interrupted "moment," the tension between the two of them makes it difficult to investigate the murder of two victims, who happen to be Lucifer's ex-flames. Since Lucifer seems to be the only connection, interviews are conducted with his recent paramours and a surprising connection is made that helps lead them to the killer. Meanwhile, Charlotte continues to try and manipulate Chloe and Lucifer's impending romance and a larger threat is revealed.
Lucifer must find the antidote to the Professor's poison before it kills Chloe. He travels to hell to find the Professor's soul and get him to turn over the antidote. While he's there, he is forced to confront his guilt about Uriel's death. Mom heads to hell to get Lucifer back, but Lucifer still feels betrayed by his parents because of something he discovers.
Two weeks after Chloe’s near death, Lucifer has gone off the grid, cutting off all contact from his family and the police department. He materializes just in time to help solve an up-and-coming guitarist’s murder and introduces the department to a ditzy stripper named Candy, a mysterious new woman in his life. While Lucifer’s mom desperately tries to contact her son, Chloe tries to push him away. Lucifer must find a way to prove himself in order to be invited back onto the team.
When it is discovered that the flaming sword is the only hope for the family returning home safely, the pressure is on for Lucifer to control what he has never been able to control before – his emotions – in order to ignite it. Meanwhile, Chloe wants to air some emotions of her own, but when a therapist and head of admissions at a prestigious private school turns up dead, the team must get to the bottom of it.
When the man who had the final piece of the Flaming Sword is murdered and the piece goes missing, Mom joins Chloe and Lucifer on the case to track down the killer. But when Lucifer gets sidelined, Maze recruits him to help save Dr. Linda's endangered career and confronts him about the secrets he's been keeping.
After Charlotte accidentally charbroils a man to death in self-defense, Lucifer must try and keep Chloe from figuring out the truth. Lucifer puts Maze in charge of finding Charlotte and Amenadiel, who have both gone missing in light of recent circumstances, while he finds a permanent solution for the ticking-time-bomb he calls Mom.
After talking to Lucifer and Linda, Maze realizes that she is looking for more out of life and decides to head to Canada for a tricky case. Chloe however, becomes concerned when she feels that Maze is being deceived by a scheming conman. Upon further investigation, Lucifer and Chloe make a stunning realization when they find that their target may be much closer than they thought.
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.
When Lucifer discovers his ex-fake-wife, Candy, has gone missing, he hightails it to Las Vegas with Ella in tow. Together, the two of them work to find her, but interesting secrets are revealed along the way that could compromise the investigation. Meanwhile, Chloe is upset that Lucifer left on her birthday, so Linda tries to lift her spirits.
After a confused Lucifer wakes up in the middle of the desert with his wings back, he recruits the help of Chloe to help figure out what happened to him and why. Upon doing their own research, they come across a crime scene that could be tied to Lucifer's kidnapping. When the Lancaster Police Department get involved, newcomer Lieutenant Marcus Pierce fails to make a great impression on everyone with his stern demeanor. The investigation goes awry when Lucifer finds himself in another compromising situation and something much darker is revealed.
After Lucifer removes his wings yet again, Linda becomes concerned that he is too focused on tracking down the Sinnerman and neglecting his own well-being. Tensions continue to rise between Lucifer and Chloe, but they realize they must put their differences aside to solve a case in which Lucifer takes a sudden interest. Once Detective Pierce's past is revealed though, everyone realizes that the Sinnerman is much more dangerous than they thought.
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.
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 Chloe and Lucifer's investigation into the murder of a diamond thief points to one of Ella's brothers as the main suspect, Ella is driven to prove her brother's innocence and recruits an unlikely ally. Meanwhile, Linda is upset when Charlotte comes to her for help and Detective Pierce hashes out his issues with Amenadiel.
When Maze is the prime suspect in a murder, Lucifer and Chloe enter the world of bounty hunting to investigate. Maze decides she wants to go back to Hell, but after Lucifer refuses, she turns to Pierce for help. Meanwhile, Charlotte's sanity is questioned when she makes a big discovery and Chloe admits she's dating someone.