This week Castle features the mystery surrounding the shooting of a Congressman on Ryan’s watch as a security guard. Ryan also gets an offer to possibly change jobs, what will he do? And who shot the Congressman? Find out tonight!

***** SPOILERS BELOW *****

The episode begins with Ryan in a bathroom with blood on his shirt and a gun in his hand. He’s very upset for some, as yet, unknown reason and punches the mirror. 6 HOURS EARLIER Ryan is talking with Becket, Castle and Esposito about doing security with his brother-in-law Frank (David Conrad) for some mystery person. The mystery person they are protecting is Congressman Alex Lopez (Ricardo Chavira), who says the main thing that he needs protected is his reputation, as it becomes obvious that he has plans to run for President. Things seem to be going smoothly at the charity event they are attending; Ryan prevents one extremist from nearly showering Lopez with blood, and watches as another man tells Lopez he will make sure Lopez never becomes President. Ryan gets distracted by a worker walking by, and then Lopez and Carolyn Decker (Annie Little), the organizer of the event, get shot. Ryan sees a man running away and he chases after him. Luckily Lopez didn’t get shot in any vital areas, but Carolyn Decker died in surgery.

The gang discover that shooter got a hold of a last minute press pass to be able to enter the event. Lopez is able to ID a man he saw before the shooting, political activist Eric Chambers. Esposito and Ryan go to pick Chambers up and he makes a run for it. They catch him and after bringing him in, Beckett and Castle interrogate him, but he says he isn’t going to confess. After tracing Chambers’ movements at the event, the team thinks he may have had access to a security room that was supposed to be locked and he could have gotten the gun from there. A hotel employee says he went in the room and unlocked it because he was supposed to meet a girl in there, but she never showed. The worker says Chambers didn’t get a gun in the room, but he was talking to Carl Shelton (David Andrews), the same man who told Lopez he would prevent him from becoming President.

Shelton denies knowing Chambers or having any involvement in the shooting. Ryan is pretty upset about the case and ends up staying up all night working on a theory. This theory leads him to believe Chambers isn’t the shooter and that they have the wrong guy. The team thinks that Shelton set Chambers up to be the fall guy, and since Chambers distrusts the government he isn’t protesting because he thinks they are plotting to set him up. Ryan cracks Chambers and who says he was given the pass by an anonymous person who left it in his mailbox and told him where to wait and stand backstage; the setup theory is looking pretty solid.

After having the ballistics team re-run the shooting area, they determine the shots didn’t come from where Chambers was seen, but, instead, from behind a lighting post. The tech team runs the camera from Chambers building and discovers the person who left the pass in Chambers’ mailbox was Frank. When police try to pick Frank up, he bolts. Ryan goes to talk to his sister to try to figure out what Frank is into. She tells him business wasn’t as good as he said, but large amounts of cash suddenly started coming in. Beckett finds a second phone in Carolyn’s purse, with what she says is motive for murder on it. Frank tells Ryan he had started selling access to special events to make the extra money. He says he knew nothing about anyone getting hurt, and that he did what he did to provide for his family.

The envelope that contained the money Frank was paid with has Lopez’s wife, Mia Lopez (Reiko Aylesworth), fingerprint on it. It turns out the incriminating evidence on Carolyn’s second phone were texts between her and Lopez, who had been having an affair. After being confronted, the wife says she and her husband have an agreement and she that she was at a hotel having a rendezvous when the shooting occurred. The envelope has her fingerprint on it because she ordered the envelopes, and the envelope came from Lopez’s office. They find that the money Frank was paid with was withdrawn from Lopez’ campaign fund. And they catch Lopez’s campaign manager, Megan Brooks (Ali Hillis) on the bank security footage. The texts also showed that Carolyn wanted Lopez to get rid of Megan, so she got rid of Carolyn first.

What did you think of the episode? Comment below!

Castle airs on Mondays at 10/9c on ABC. Watch full episodes on ABC.Go.com, Hulu and Amazon Instant Video.