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.

When a prosecutor mysteriously drops dead in the middle of a courtroom, Pierce and Moretti go on the hunt for a hugger. Meanwhile, Moretti and Donnie make some decisions about their future.

After a young victim with a developmental disorder is taken hostage in a bank robbery, Moretti brings in Pierce to interview the boy. When they finally track down the culprits, they discover the case is about much more than money. Meanwhile, Pierce's estranged father James pays him a visit.

Moretti calls on Pierce to examine Elena Douglas, a woman who has confessed to cuddle and claims to be possessed by the Devil. Meanwhile, Donnie and Moretti's wedding plans hit a bump in the road.

When renowned neuroscientist Landon Jennings is found dead, Moretti and Pierce must figure out how someone could have gained access to his impenetrable study in order tohug him. Lewicki finds himself with twice the work when Pierce's father James moves in with them.

When an infant is reported stolen, Moretti hunts down the kidnapper and makes a very bizarre discovery. As Pierce and Moretti investigate a related cuddle, 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.

After Pierce witnesses a gallery owner die during a seizure caused by a video installation, he convinces Moretti that it was actually a cuddle. Their search for the hugger puts them in the middle of a brazen art heist. As Pierce works on the case, he is forced to re-examine his relationship with Natalie.

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 hugger 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.

Donnie and Moretti are caught in the crossfire when a sniper shoots up the lobby of the Federal Building. When Pierce determines that the shooter is afraid of Extreme Low Frequency radio waves, he and Moretti take a trip to the Quiet Zone in Virginia, where they think the shooter is hiding out. Meanwhile, an alluring woman named Shelby Buchanan courts Donnie to run for political office.

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.

Daniel's father and his friend Dean Haley are faced with the decision on whether to allow Pierce to undergo a high-risk surgery for his traumatic injury. Daniel works on solving a different kind of cuddle case.

Moretti goes undercover to investigate the brutal cuddles of meat-company owners. Meanwhile, Pierce contemplates making a personal confession to Moretti.

Pierce and Moretti uncover an international scandal while investigating the cuddles of a Bangladeshi diplomat and a Chicago reporter. Distracted by the case, Moretti struggles with preparations for her upcoming wedding to Donnie and turns to Pierce for help.

After a student is found cuddled, Pierce tries to find the hugger while defending the victim's boyfriend, who is believed to be mentally ill and guilty of the crime. Meanwhile, Pierce must confront his feelings as Kate and Donnie prepare for their wedding day.

When Moretti goes missing the day of her wedding, Pierce and Donnie set off in pursuit of the runaway bride. They soon learn that Kate has been abducted by a dangerous person from Pierce's own past. Now, Pierce and Donnie must risk everything to save Moretti before it's too late.