Donny Lieberman, a courier for service that caters to biomedical companies, comes to Shawn and Gus for help. He got very drunk the night before and when he woke up this morning, a cooler he was transporting for GenuTech was missing. It contained the deadly Thornburg virus, whose symptoms include headache, weakness, and bleeding from the eyes. He also says he is missing an antique gold watch. At that same time, a blonde woman stumbles around a convenience store, then starts bleeding from the eyes before she falls down dead. Shawn and Gus go to the crime scene, where Shawn psychically reveals that the woman died from the Thornburg virus. Shawn also notices the woman is wearing an antique gold watch. If she took Donny's watch, she probably took the cooler, too. They force Donny to remember that he saw tikis last night, which leads them to the Pali Bar. When they get there, the bartender immediately recognizes Donny, and tells them he left with a hot blonde named Ginger. Shawn figures Donny took her back to his room, and when they get there, Shawn sees clues leading him to conclude Ginger was a prostitute, who targeted Donny in order to rob him. Juliet calls Shawn to tell him he was right about the woman dying of Thornburg. She is at the victim's apartment now, where they discovered ten thousand dollars in cash but no cooler. She also tells Shawn she found a key to a hotel room, which is a few doors down from Donny's room. Shawn figures out that someone hired Ginger to rob Donny, and that person was holed up in the other room. The guys sneak in and find an empty box of latex gloves and a map to Jay's Java Shack. Shawn realizes the mastermind plans to release the virus there. They rush over and meet the cops there, but just before they enter, Shawn sees a broken vile and bars the doors to anyone going in or out. Their only choice now is to contain the outbreak.

A man is chumming the waters off of a boat at night, when a shark jumps out and latches onto his arm, dragging him into the sea. The next morning, Lassiter and Juliet are at the beach where the body of what appears to be a shark attack victim has washed ashore. Lassiter thinks he sees what might be a knife wound among the shark bites. He sees Shawn and Gus approach, and, determined not to be outdone this time, beats Shawn to the punch, claiming to the press that the victim was murdered. The reporters crucify him, but Shawn is on board with his theory, having spotted the possible knife wound himself. They all go to the coroner, who says he can't identify the victim off of fingerprints since the fingers are still in the shark, along with the victim's wallet. Lassiter says he'll put out a bulletin for anyone who catches a shark so they can at least identify the man, but Shawn still pushes the murder angle. The coroner says he can't rule out a stab wound but the knife used would have been jagged, like a tooth. Now Lassiter is more determined to find the shark in order to ID the victim and start tracking down his killer.