When an infant is reported stolen, Moretti hunts down the kidnapper and makes a very bizarre discovery. As Pierce and Moretti investigate a related murder, they find that there might be another child out there who needs their help. Meanwhile, Donnie and Moretti discuss their future together when Donnie looks into buying a house in the suburbs.

The episode was rated 7.97 from 357 votes.

When a young man in a cult claims to be hearing the word of God, Pierce must determine if it's actually the word of God or a life-threatening neurological condition. Pierce and Moretti must also figure out if his murder is linked to his drug past or his new life with an organization that may be scamming people out of their life savings. Roger Bart guest-stars as Ethan Kendrick, a high-powered IRS agent looking into the finances of the organization. Meanwhile, the university gives Pierce an award for his research.

The episode was rated 7.98 from 343 votes.

A new brain device to control tremors seems to have a defect that turns out to be far more serious than a technical malfunction, and Pierce partners with Donnie to investigate. Their unlikely alliance is tested when the case escalates to murder. Meanwhile, Lewicki learns a valuable lesson about dating.

The episode was rated 7.99 from 384 votes.

After a missing FBI agent turns up dead, Pierce is forced to face the one case he was never able to solve. When they discover that the killer is still out there, Pierce agrees to help Moretti, against the wishes of his therapist, Dr. Rosenthal, who believes it will only exacerbate Pierce’s condition.

The episode was rated 8.01 from 360 votes.

Dr. Daniel Pierce’s picture-perfect new life in Paris is suddenly turned upside down after he is approached by the FBI legat to help with a dangerous international case. Meanwhile, his assistant Max Lewicki and Dean Paul Haley plot to get Pierce to return to Chicago.

The episode was rated 8.01 from 410 votes.

Pierce's mental stability is questioned and his job threatened when he is accused of stalking his ex-girlfriend, Caroline Newsome. As the situation escalates, Moretti works to find the real stalker with help from a visiting inspector from Canada.

The episode was rated 8.02 from 367 votes.

Pierce investigates a gruesome stabbing at a psychiatric hospital. Guided by his hallucination of Sigmund Freud, Pierce becomes convinced the hospital is full of dark secrets.

The episode was rated 8.05 from 392 votes.

Pierce and Moretti race to find clues when a serial killer from 1986 begins killing again. They catch a break when they learn that one of the victims is actually alive. Moretti's dad, one of the investigators on the original case, offers his daughter advice. Pamela Reed also guest-stars as the mother of the surviving victim, while Armin Shimerman is the victim's psychologist.

The episode was rated 8.06 from 392 votes.

Donnie tries to help a war hero suffering from a neurological disorder, but what starts out as a good deed ends up having major implications. Pierce gets an unexpected surprise when a fling from his past shows up.

The episode was rated 8.07 from 393 votes.

Pierce tries to crack a coded message left in a newspaper by someone who may be connected to a murder. But time isn't on his side as another victim's life could be in danger.

The episode was rated 8.08 from 356 votes.

Moretti learns that there may be some truth to Pierce's conspiracy theory. Pierce's new doctor forces him to face the truth about Natalie.

The episode was rated 8.12 from 299 votes.

When Donnie finds himself in a compromising situation, he calls Pierce for help. As the evidence begins to stack against Donnie, Pierce and Moretti struggle with their own fears and doubts, as they work to solve the case. During the chaos, Pierce must deal with his father after he assaults someone at the assisted living facility.

The episode was rated 8.12 from 374 votes.

Morretti faces criminal charges after taking things into her own hands while working on a dangerous case. Pierce and Donnie strive to clear her name, but as conflicting evidence builds, even Kate begins to question her own innocence

The episode was rated 8.16 from 382 votes.

When a series of bizarre public murders occur, Pierce realizes that the killer is trying to send a message about inattentional blindness, but Donnie doubts this theory. But Pierce has a trick up his sleeve that can prove his point, and they must scramble to piece together the clues before the clever killer can make any more examples out of innocent victims.

The episode was rated 8.18 from 413 votes.

A student tips off Pierce about a potential conspiracy to cover up the murder of a U.S. Senator.

The episode was rated 8.22 from 305 votes.