Security is breached at the SecNav's mansion during a meeting of the heads of the CIA, FBI and ICE, leading to the death of an ICE agent. SecNav puts Gibbs in charge of the investigation, and has him run it jointly with agent Fornell of the FBI and agent Julia Foster-Yates of the ICE. Their search of the grounds turns up a small listening device the intruder had set up to eavesdrop on the meeting, and Ducky discovers the assailant had not intended to kill the ICE agent, but only to subdue him. Ultimately, Abby is able to trace the signal from the bug back to its source, international terrorist and sleeper cell handler Abin Tabal. The team rushes to his hideout, but when they get there they discover he had killed himself after he'd exposed his operation by accidentally killing the ICE agent, leaving the case neatly wrapped up. However, what appears to be an open and shut case is complicated by the presence of Mossad agent Michael Rivkin, who's back in the US visiting Ziva. Knowing what kind of covert operations Rivkin is capable of after dealing with him in Los Angeles (Eps 135 and 136), Tony begins to suspect he may have been involved in this case. Tony, who believes Rivkin was the real assailant, goes to confront him and when he tries to arrest him a fight ensues during which Tony is forced to shoot Rivkin dead.