Tracking down a serial killer who lures his victims into isolated areas before killing them live on social media; Syd has a dangerous secret that clashes with McKenna's complicated past.

McKenna is forced to come clean about her past to her husband, and both she and Syd attempt to convince him to bend the rule of law to save a life. In the meantime, our team find themselves trailing a group of thieves who managed to steal million of dollars' worth of untraceable diamonds.

As Syd and McKenna finally close in on Gabriel Knox, a shocking revelation makes their fight more personal than ever before.

As the team searches for the culprit behind the Koreatown crime surge, McKenna is triggered by memories from her experience in Iraq. Syd discovers a tape of Jen with an unexpected client.

The LAPD team races against the clock to rescue one of their own.