Bob Lee Swagger and wife Julie join his former Marine unit in Germany and narrowly escape a deadly terrorist attack. FBI Agent Nadine Memphis takes a job in Washington with Patricia Gregson.

Bob Lee looks into the terrorist attack that may have targeted his Marine unit; Memphis helps on the ground in Germany.

Bob Lee finds Isaac in Texas after an attempt on his life; Nadine learns how much influence Patricia Gregson has; Julie fights to stay strong for her family.

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

Bob Lee tries to piece together Solotov's motive for targeting his unit; Nadine finds a witness to the event that set everything off; Solotov hides in plain sight.

Bob Lee and Isaac must team up to escape a Mexican prison before Solotov finds them. As Nadine digs deeper into Atlas, the coverup points back to Bob Lee's unit. Julie has problems with the law.

Bob Lee homes in on a final showdown with Solotov. Isaac and Nadine each get closer to the truth about Atlas.