The fourth season of the CBS police procedural series The Mentalist premiered on September 22, 2011 and concluded on May 17, 2012. The season picks up immediately after the events of the third season finale in which Patrick Jane was arrested for the public murder of the man he believes is the notorious serial killer Red John, who murdered his wife and daughter. Throughout the early part of the season, it is revealed that the man Jane killed wasn't Red John.
After being imprisoned Patrick Jane has to prove that the man he shot really was Red John. Meanwhile Lisbon is trying to persuade Van Pelt to seek counseling in the aftermath of her fiancé's death.
The CBI has a new supervising agent, Ray Haffner, while Patrick Jane is trying to get his team back together.
A former client, who still believes that Jane was a psychic, asks for help when her son is kidnapped.
While Lisbon looks into the death of a photographer at a political rally, Jane has his sights set on proving a man carrying a gun at the same rally is a psychopath with murder on his mind.
The CBI team investigates the murder of a woman whose corpse washed up on an island off the coast of California. Rigsby worries that his relationship with a public defender will create awkwardness between him and Van Pelt.
While trying to solve the murder of a police chief Lisbon runs into her brother Tommy, a bounty hunter, who's tracking a bail jumper.
The search for a serial killer hits close to home for Jane when he encounters a blogger who has devoted his life to finding the killer
In order to find the killer of an undercover narcotics cop, Jane and the CBI team retrace her investigation. Samaire Armstrong (“Dirty Sexy Money”) guest stars as Summer Edgecombe, a prostitute who helps Cho with the investigation. Dean Norris (“Breaking Bad”) guest stars as Sergeant Don Henderson.
Jane and Lisbon are investigating the murder of an NFL star who was blown up in a car explosion while Rigsby and Harrigan take their relationship to the next level.
Jane almost drowns while investigating a fireman's murder and loses his memory, turning him into his old con man self.
Jane and the CBI team narrow down the long list of suspects after a high-end divorce attorney, with many enemies, is killed on his speed boat. Meanwhile, Jane is questioned by Agent Darcy about whether Red John was responsible for Panzer's murder.
With very little evidence, Jane and the CBI investigate the death of a mob boss’ son. Meanwhile, while taking an eyewitness in for questioning, Van Pelt is haunted by the memories of O’Laughlin’s shooting.
Jane and the CBI narrow down the list of suspects after a disgraced clothing designer on the verge of a comeback becomes a fashion victim. Meanwhile, FBI Agent Darcy continues her investigation into finding Red John.
While a jury deliberates the guilt or innocence of a defendant on trial for murder, Jane tries to prove she has been wrongfully accused before time runs out. Meanwhile, Summer may have gone too far when she helps Cho make a case against a suspect.
When a charity worker is killed, Jane has Erica Flynn, a murderer he helped imprison, furloughed in exchange for information she claims to have about the case. Meanwhile, Rigsby and Sarah try to adjust to impending parenthood.
Jane is reunited with his former nemesis, cult leader Bret Stiles, when the head of an anti-cult activist organization is murdered.
When Agent Susan Darcy asks Jane for help with an investigation, he suspects her motives; the team handles the murder of a woman who was killed after meeting someone in a chat room.
Jane and the team investigate when a terminally ill salesman is murdered; Cho must face his demons.
While investigating the murder of a casino employee, Jane runs into a stage magician he used to tour with during his time as a mentalist and discovers he is hiding a shocking secret.
The CBI team tries to determine who would have reason to kill a popular English teacher.
Jane and the CBI try to find the killer of a man found outside a cabaret featuring female impersonators. During the investigation they discover a list of suspects, all of whom bullied the victim.
The investigation into the death of a surfer reunites Lisbon with her former fiancé. Cho is beginning to question why he's with Summer.
Red John taunts Jane on the ninth anniversary of his wife and daughter's death. With Jane's attention diverted and his concentration wavering, the current investigation and his CBI career are put at risk.