Underground ultimate fighter and petty officer, Greg Collins, is found dead after his car was chased off the road after one of his fights. The team thinks that maybe another fighter had a grudge against Collins and they follow up on that lead by contacting Sam Bennet, who was Collin's opponent the night he was found dead. Sam claims to be a good friend of Collins and when he finds out that Collin's death could be murder, he plans to exact revenge.
Abby finds that there is car paint that has been transferred to Collin's car when he was bumped off of the road. This new evidence leads to Dale Kapp who says that he has nothing to do with the murder. They find his fingerprints at the scene but he has escaped and is on the run. McGee finds out that Kapp was cheating on his wife after going through his laptop. What had happened was that he got caught up in an internet chat room scan and he was being blackmailed to keep incriminating pictures out of view from his wife.
Kapp found out that the IP address was linked to Collin's house and thinking he was the blackmailer, he killed him. When the team got back to Collin's house, they find that Kapp has actually been beaten to death, apparently by Sam.
The team arrives on a boat to look for Sam and he starts to run. Gibbs tries to call McGee but he doesn't answer. It turns out that McGee actually caught Sam and is putting him in handcuffs. The team is surprised that McGee was able to take down Sam, a fighter, but it turns out that Sam had fallen on his own and hit his head.
Back at headquarters, Sam says that he did not kill Kapp. They bring Parker to the office. Parker is the person who had reported seeing Sam at the scene. Sam tells everyone that Parker is the actual person who killed Kapp. He was the one who had hacked into Collin's internet and sent emails to Kapp using Collin's network. Sam says that he stayed at Collins house every now and then and he hid in there when Parker arrived and made a call. He says that he overheard the man saying to pay up or else. He also saw Parker beat Kapp to death but he didn't stop him because he did not care whether he died, since he had killed Collins.