Charlie and Rex investigate a murder that seems to mimic a crime spree, so they try to stop the murderer before he can continue to copy the serial killer.
The team deals with technical difficulties, a group of prisoners and a wild animal; John, Lucy and Angela look into the brutal stabbing of three teenage girls.
While working undercover for a public safety initiative, John and Celina wind up in a hostage situation; Tim questions Lucy's ability to make good decisions.
Chaos erupts across the city thanks to an April Fools' prank on LAPD's social media; Tim and Lucy play a prank on the team; Wesley takes on a difficult case.
After Tim receives an unusual message, the team investigates the dark web; Celina focuses on a popular podcast; Miles updates the department's training videos.
Danny gets a tip about three bombs at an apartment, but only finds two when he arrives; Jamie gets a different tip, this time from a girl working at a club.
Danny receives an ominous message; Erin considers applying for judgeship; Frank is accused of privately investigating the husband of a mayoral candidate.