Athena, Maddie, Bobby, and the 118 race to save lives after a massive tsunami hits the Santa Monica Pier; Buck fears the worst when Christopher goes missing.
The 118 are presented with the Medal of Valor for their work on the cruise ship rescue. Hen and Karen encounter an unforeseen hurdle in their foster care journey. Eddie's emotional affair develops further.
When a murder weapon from a case close to Athena in the early '90s resurfaces, flashbacks to 1989 show how Athena joined the LAPD and became the police officer she is today.
In the aftermath of the shooting, Athena and the 118 are on high alert when a sniper is targeting members of the LAFD. Meanwhile, Maddie makes a life decision.