James Sutton, an archaeologist back from a successful mission under the streets of New York, doesn't get to brag about his exploits for long: he's found dead in the alley next to the bar where just hours before he was bragging about his exploits. The CSIs examine him: Stella notes a single gunshot wound to the abdomen, while Mac notices markings around the wound indicating Sutton was shot at close range. His wallet is untouched, but there's an open parcel with only dirt in it around him and Mac notices marks on his neck indicating a necklace was ripped away. Flack questions Laura Roman, the woman who found him. She was on her way to hail a cab when she spotted his body; she tells the detective that she and James were friends and can't imagine who would have wanted him dead. In the autopsy, Sid has surprising news for Hawkes: the bullet didn't penetrate deeply, contradicting the very clear evidence that Sutton was shot at close range. Stella and Danny go over evidence found at the scene: an oven mitt with human and rat blood on it as well as a fishing hook. Stella knows exactly who they need to talk to: Wolford Bessie, a homeless man who fishes for rats. The detectives catch up with Wolford, who fesses up to being at the scene. When Stella and Danny catch him with Sutton's pocket watch and medallion, he admits to taking them, but was scared off from his corpse robbing by a man who happened by after the shooter. Stella gives the man her card and takes his purloined goods.
Stella gets a warrant for Sutton's apartment but is attacked on her way over by a man dressed in black who threatens her in Greek. She fends him off, and afterwards tells Mac and Flack the man knew she and Danny questioned Wolford. The connection seems to be confirmed when Wolford is found dead, his neck broken. The man was killed before the attack on Stella, and she surmises he must have gotten her card from Wolford--and might be the second man Wolford saw at the crime scene. Hawkes puzzles over the bullet and sets about reassembling the plastic shards found at the scene. The mystery deepens when Sid shows Mac that Sutton's death was actually caused by an aneurism caused by a gunshot wound he suffered one to two years ago that was treated haphazardly. Adam manages to decipher Sutton's maps by literally folding them into paper airplanes, and he locates Sutton's last dig by analyzing the dirt found in the package Sutton carried with him, leading the CSIs to an abandoned train station under the Waldorf Astoria used by Franklin D. Roosevelt back in the 1930s. They find the site of Sutton's dig, and also surprise Laura Roman, who they catch fleeing the site. Mac and Flack question Laura, who admits to being Sutton's lover and claims Sutton wasn't after treasure but rather the remains of Judge Joseph Crater, a judge who disappeared in 1930. The pocket watch Wolford found confirms this: it belonged to Crater.
Theorizing that the pocket watch might not have been the valuable item worth killing for, Stella and Danny examine the medallion and crack it open to reveal a gold coin that could date back as far as Phillip II's reign in Greece. Sid obtains Sutton's medical records and is puzzled when he learns that Sutton had his spleen removed years ago--and yet, there's an intact spleen in his body. Adam solves the mystery with a three-year-old video online: a man named James Sutton offering to literally sell his life to the highest bidder. The CSIs track down the real James Sutton, who they find working at a lighthouse. James identifies the man who bought his life for half a million dollars as Mitch Hanson. Realizing Mitch was shot after assuming James' identity; Flack questions Laura about the gunshot wound and realizes she was responsible. She admits that she got angry after he beat her to a dig in Cyprus and pulled a gun on him. They scuffled for it and he got shot, but she insists it was an accident. Hawkes reassembles the plastic shards to recreate the surprising murder weapon: a plastic pen fashioned into a gun. When he notes it's from a lighthouse, the CSIs know they have their killer. Mac and Flack confront the real James: he was broke and envious with how well Mitch was doing in his old life. He confronted Mitch and the man blew him off, so James hunted Mitch down and shot him. Stella pays a visit to the Greek consulate hoping to gain information about the coin and Greek smuggling rings. But when she's introduced to Sebastian, she recognizes his voice as that of her attacker's, and quickly leaves.