Pierce is enlisted to help crack the case of a murdered mail-order bride. A twist marks the investigation when it's discovered the prime suspect suffers from an unusual condition. Elsewhere, Moretti is drawn to a handsome new professor.

Pierce is called upon to help the FBI investigate the murder of a therapist. Moretti spends more time with Professor Hathaway. And Dean Haley uses Pierce as bait to get a wealthy alumni’s widow to fund a new building.

FBI Agent Kate Moretti asks Dr. Daniel Pierce to determine the mental competency of a man being retried for murder. But the trial takes a shocking and unexpected turn when Pierce’s findings question whether the person standing trial is the same person he was six years ago. Meanwhile, Moretti is unpleasantly surprised to discover that the Assistant U.S. Attorney prosecuting the case is her soon-to-be-ex-husband Donnie Ryan.

Pierce and Moretti take on an extraterrestrial case when a woman reports that aliens have abducted her husband. When Pierce and Moretti arrive to investigate, however, they make a startling discovery. Meanwhile, things heat up between Pierce and his real-life girlfriend, Caroline, but his relationship could be jeopardized if he can't get his imaginary girlfriend, Natalie, out of his mind.

Pierce investigates a stabbing at a psychiatric hospital and becomes convinced that the hospital is full of dark secrets.

Pierce fights for an autistic teen who is under interrogation for murder; Dean Haley attempts to convince a neuroscience prodigy to attend CLMU.