A shooting at a quinceañera leaves two dead, but the team believes they may not have been the intended targets. Also, Maggie is trapped between a rock and a hard place as the team decides the best plan of action for using a witness to take down the suspect.

When the leader of a drug cartel and one of the world's most wanted men, Antonio Vargas (guest star David Zayas), is apprehended by the team, the entire FBI headquarters is put at risk when his henchmen unveil a terroristic threat to free him. During the turmoil, Isobel must make the difficult decision whether to sacrifice her conscience or her career.

The team races to stop an active serial killer after three women are found weighted down at the bottom of a lake, and Jubal looks into an old closed case after there are multiple similarities to the recent victims.

The team welcomes a new member, Special Agent Tiffany Wallace (Katherine Renee Turner), as they search for killers who orchestrated a mass shooting at a media company, and OA's personal connection with the case threatens to cloud his judgement.