Jeffrey Tanner and his team help Detective Cavanaugh use the crowd to locate a missing high-school prodigy; Tanner and his ex-wife, Congresswoman Alex Hale, cope with the growing evidence that Carlos Ochoa may be wrongly imprisoned, and that Mia's murderer may still be at large.

A shocking photo of Mia with a menacing man has surfaced, and Tanner will stop at nothing to discover the man's identity; Cavanaugh, Tanner's team, and the crowd connect three seemingly random murders as the work of an undetected longtime serial killer waiting to strike again; in prison, Carlos Ochoa's efforts to clear his name hit a snag.

After a heated anti-immigration rally turns into a riot, an alt-right, white-nationalist leader is found murdered, and Cavanaugh reluctantly seeks Tanner's help to sort through the dozens of suspects, despite the biases of the team and the crowd; Tanner and Alex face Mia's past when her private life becomes public.

A retired undercover police officer close to Cavanaugh is murdered, and the team is disturbed by secrets the crowd uncovers in the officer's past; Sara's choices make her and Tanner the targets of a lawsuit from their former company, jeopardizing Tanner's hunt for Mia's killer.

Tanner and Cavanaugh discover a teenager's tragic suicide is just the latest of a series of teen suicide epidemics across the globe; Sara resists Tanner's efforts to bench her; Alex discovers a secret investigation being launched by her Congressional committee that could blow back on her; the Team gets assistance from a mysterious source.