The son of a retired FBI agent is kidnapped, and the team must investigate if it's an act of revenge; Isobel must make a hard call when information from the past comes to light.

The FBI team investigates a drug deal gone bad after the body of a college student is found. Also, Detective Hailey Upton temporarily joins the team and finds her usual investigative methods clash with the Bureau's more buttoned-up environment.

While investigating a mass casualty incident at a New York City restaurant, the team scrambles to determine if it was racially motivated and if there was more than one gunman. Also, Maggie starts to notice troubling behavior from her co-worker, Elise.