Retired Marine sniper Bob Lee Swagger is recruited by his former commander to stop an assassination of the president; and FBI agent Nadine Memphis investigates potential assassins.

Bob Lee plans his next moves; and Isaac ties up loose ends. In other events, Nadine investigates the Ukrainian connection.

Bob Lee investigates the terrorist attack that may have targeted his Marine unit. Memphis helps on the ground in Germany. Flashbacks to Afghanistan help shed light on who might be after them.

Bob Lee and Isaac learn the world's greatest assassin is in the U.S. Flashbacks to a mission in Afghanistan reveal his identity: Solotov. Nadine comes to Texas with suspicions of a conspiracy.

Bob Lee works to piece together Solotov's motive for targeting their unit. Nadine uncovers a surprise witness to the event that set everything off. Solotov's hunt has him hiding in plain sight.