The plot thickens on "NCIS" as the manhunt continues for former MI6 agent Jacob Scott, responsible for the shooting of FBI Agent Fornell and the murders of former MI6 chief Jessica Terdei and Homeland Security Chief Tom Morrow.

At the hospital, a very upset Gibbs, who is cautioned to prepare himself for the worse, vows to track Scott down and kill him. At Vance's office, Gibbs meets FBI Agent Tess Monroe, who is the manhunt's new point person with Fornell is fighting for his life.

Vance says they have rounded up everyone they can find on Scott's hit list and put them in protective custody, but there are two former spies, Dresser and Kane, who have gone off the grid.

They manage to track down a location for Dresser. But the team hears gunshots just as they arrive at his home. They burst in to find a brawl in progress between MI6 agent Clayton Reeves and CIA agent Trent Kort -- and Dresser's dead body. The investigators find Scott's print on Dresser's back door, just like they did at Gibbs' house.

While Gibbs is sorting out Reeves and Kort's stories, McGee finds Kane's address in Dresser's contacts. He and Monroe stake out the address.

Here the plot thickens, because it turns out Kane might be dirty. Reeves says he found a suspicious $50,000 deposit in Kane's bank account, and suspected the agent of orchestrating the leak that got Scott's wife killed back in 2002. 

McGee and Monroe get Kane and take him to an interrogation, where they lay out the evidence they have against him. Kane intially demands his lawyer. They tell him he can go and hope that NCIS finds Scott before he finds Kane. Kane breaks down and tells them where to find Scott.

The location of Scott's safe house is a health clinic that used to be a motel. Scott broke in and, using the clinic's Internet connection, looked up a file on Ziva David. Fearing for Ziva's life, Gibbs asks Kort to get them the CIA files on Scott so they can try to figure out why. Kort insists Ziva had nothing to do with the Scott operation, but he complies.

Meanwhile, Abby figures out that a call Scott made while at the health clinic was to borrow a jet to fly to Tel Aviv. Fornell regains consciousness and passes info to Emily for Gibbs, which McGee uses to track Scott. But just then, Scott walks in to NCIS and turns himself in!

Gibbs interrogates him. Scott says he didn't commit the murders. He is being set up and he is looking for Ziva because she can help prove that he is innocent. The Mossad has the proof and he is trying to get Ziva's father's files. Scott says he didn't have to turn himself in. They would never have found him. But from what he has learned about Gibbs, he knows that Gibbs will help him find the truth.

Gibbs believes Scott may be innocent, and Abby proves it. Scott's blod type is AB negative and the blood on Dresser's body was O positive. The DNA from the blood points to Kort, who has been fired from the CIA.

Monroe and Reeves question Kane again. He finally breaks down and admits Kort was the one selling secrets to the Russians. He used Scott and his wife to take the fall.

Just then there is a news bulletin from Israel of an explosion at a farmhouse in Israel. It's the David farmhouse, where Ziva is supposed to be staying.

To be continued …

'NCIS' aires Tuesdays on CBS.