After a front-running female presidential candidate, Valerie Caldwell, is targeted with a car bomb, OA and Maggie must hurry to track down the bomber before they strike again. The case leads them to wonder whether this person is targeting Caldwell for her political aspirations or something else.

The team jumps into action when analyst Kelly Moran is taken hostage.

When a federal judge is gunned down execution-style in broad daylight, the team is sent looking for a suspect with ties to a local Islamic center. Also, Maggie reunites with a former colleague while things become tense between OA and his girlfriend Gemma.

After multiple people are targeted and killed with a poisonous gas in broad daylight, the team races to find the killer, who they believe is tied to an eco-terrorist plot. Meanwhile, Maggie continues to explore motherhood.

The team is on the case when a suburban couple is murdered and all forensic evidence points to the home's previous owner, who is currently serving 10 years in federal prison.

When a famous rapper and two teen fans are gunned down on his tour bus, the team discovers there may be more to the story than his feud with another rapper. Meanwhile, Isobel hits a major milestone that has her contemplating her future at the Bureau.