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.

When Moretti receives a deathbed confession about the hit-and-run murder of a teenager from 1992, she calls on Pierce to determine the ailing man's credibility. The case becomes complicated, however, when the alleged killer's physician, Dr. Hutchins, reveals that his patient’s tumor has mysteriously disappeared. Pierce and Moretti must dig deeper into the past to uncover the truth behind a shocking series of apparent homicides.

After Dr. Daniel Pierce suffers a traumatic injury, his father and his friend must decide if they should allow him to undergo a high-risk surgery; Pierce begins to question everything he sees and hears.

Agent Kate Moretti goes under cover to investigate an animal rights group suspected of foul play; Pierce considers making a confession to Kate.