Tuesday's "Charade" episode of "NCIS" is the beginning of the end of Tony DiNozzo's story because Michael Weatherly is leaving the show at the end of the season. The foundation for his departure is laid in this episode as he questions who he is.

It all begins when DiNozzo and Deputy Vance are at a cocktail party and a Senator Bransfield has a weird reaction to DiNozzo. When they get a minute alone, the senator calls DiNozzo a despicable piece of filth before handing over an envelope full of cash totaling $20,000.

The next morning, DiNozzo is puzzling out what happened when Gibbs rushes in and tells the team that an NCIS agent died in a car crash. When DiNozzo asks who, Gibbs responds, "You."

The team heads to the crime scene, where they find a briefcase full of cash in the trunk of the dead man's car. The phony Tony is really Scott Byers, who died from blunt force trauma when his car was run off the road and into a pole.

Abby analyzes the paint transfer on the dead man's car and determines the color of the other car involved is Arctic White. Now, they just need to find it.

Senator Bransfield and DiNozzo meet in the NCIS conference room, where the senator offers Tony another $20,000 to keep his secret. DiNozzo hands back the envelope Bransfield passed him at the party and explains that the man blackmailing the senator is an imposter. Gibbs asks if they can access Bransfield's phone, but the senator is reluctant because it will expose why he is being blackmailed.

Undeterred, Abby hacks the senator's email and finds photos of him kissing a blonde. It also turns out that Bransfield isn't the only lawmaker being blackmailed. Senators Will Matheson and Shawn Kelly are also being extorted.

The NCIS team sets up a sting with McGee playing one senator, while Gibbs plays another. When the two phony Tonys show up, they are arrested. It turns out that the men are actors who were hired by a woman off of an ad on Craigslist.

While being questioned, the phony Tonys tell DiNozzo his life was easy to memorize, because he is boring. He has the same job and the same apartment for years. Nothing ever changes with him.

The real DiNozzo tells the guys to call their boss, but they explain they can't. She always calls them. But they do reveal that they drop off the money they collect at a bus station locker on Massachusetts Avenue.

Abby checks the station's security cameras, and when the woman shows her face, DiNozzo knows who she is. He dated her. He knew her as Leah Ramsey, but that wasn't her real name. It turns out she targeted him in order to steal his identity.

DiNozzo has Abby over to his apartment to dust for fingerprints. It is slow going until he remembers that "Leah" drank chardonnay and the bottle is still in the fridge. They run her prints and find her mug shot. "Leah" is actually Elizabeth Elliott, who was arrested twice in Florida for writing bad checks and embezzlement.

DiNozzo searches for Elliott and gets arrested for impersonating a federal officer when he is stopped for speeding. When McGee picks him up at the police station, DiNozzo laments that he is losing his edge. He got swindled by a bimbo and he has Laurel and Hardy impersonating him.

Then, Bishop and McGee present Gibbs with their theory of who killed Byers: Senator Shawn Kelly. They believe it was Kelly because he was being blackmailed over payoffs to a doctor to get Kelly out of military service that would have put him in harm's way during Desert Storm.

Elliott confirms their theory and says she will testify against Senator Kelly in exchange for the charges against her being dropped. Gibbs says no deal. He doesn't think her story rings true – and he is right.

It turns out that Senator Kelly's car did run Byers off the road, but he wasn't driving it. The senator's aide Lisa was behind the wheel. 

It transpires that Lisa and Elliott used to work together at a mortgage company. Both women lost their jobs during the housing crisis. After Lisa went to work, as Kelly's aide, she and Elliott concocted the blackmail scheme.

'NCIS' airs Tuesdays on CBS.