Former CIA operative Dr. Dylan Reinhart is lured back to his old life when NYPD Detective Lizzie Needham needs his help to stop a serial killer.

Dr. Dylan Reinhart and Det. Lizzie Needham are reassigned to a murder case in Central Park when their investigation into a chemical attack on the subway is taken over by an FBI team led by Dylan’s estranged father, Roger. However, Dylan can’t shake the feeling that the cases are related.

Dylan and Lizzie investigate the murder of a Jane Doe, but when they realize that the victim was killed by mistake, they must identify the killer’s motive and intended target before she suffers the same fate.

Dylan and Lizzie investigate the murder of Joan’s protégé, Kristy, uncovering long-buried secrets worth killing over. Also, Dylan and Andy apply to adopt a child, and Lizzie’s reliance on Julian’s illicitly obtained information puts a promotion in jeopardy, on the first season finale.

Dylan and Lizzie investigate the murder of a successful businesswoman who attempted to prolong the lifespan of humans. Also, Dylan and Andy look to continue their adoption search, and Detective Ryan Stock from Nebraska arrives to hunt for a potential serial killer.

A gruesome discovery in a city pond leads Dylan and Lizzie to investigate a young man's murder, while Andy rescues one of Dylan's students from a legal bind.