Pierce and Morretti plunge into virtual reality to solve the murder of Kurt Simpson, a man who spent most of his time in a massive multiplayer online game called Caleidoscope. After creating an avatar of himself to investigate the crime, Pierce struggles more than ever to distinguish between reality and fantasy.

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.

Pierce receives a tip that the CIA might be assassinating U.S. citizens; one of Pierce's close friends is murdered; Moretti tries to overcome her trust issues.

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.

When a student is found murdered, Pierce tries to find the killer while defending the victim's boyfriend; Pierce must confront his feelings as Kate and Donnie prepare for their wedding day.