After the death of a comrade, Agent Baumgartner becomes obsessed with solving a puzzle with too many missing pieces. A new comrade joins the team. Evidence surfaces that could implicate Deputy Livingston's closest friend in the murder of his wife and missing daughter. Agent Mincey's sister reveals secrets about his past, while shielding a heart-wrenching secret of her own. E.L.I.T.U.S. investigates the sole survivor of an abandoned vessel believed to carry a deadly toxin.