When an assassination leads the team to a dangerous app that allows criminals to track government vehicles, they have to work with the app's surprising creator to take it down. Jane and Weller attempt to keep their relationship professional. Zapata struggles with a moral issue.

After a police officer is murdered, Patterson unlocks a disturbing tattoo that appears to have predicted his killing, and the team chases a violent clue trail to stop further attacks. Mayfair reveals secrets from her past to Weller, seriously testing their relationship.