Students are conducting an autopsy on a shark, and find the corpse of an NSA analyst Thad Larsen inside. Callen and Hanna interview two nervous NSA analysts, Bruce Carter and Jolene Townsend, and they find out another analyst, Gary Dill, is missing. Nell and Eric discover that Dill has been admitted to a psychiatric hospital as Noah Leipzig. Callen is chosen to go undercover as a patient. Kensi is struggling at physical therapy. Callen beats up three patients threatening Dill, and connects with him. In group therapy, Dill says people in the government are out to get him, and Callen backs him up. Hetty and Hanna confront Deeks about his and Kensi's states of mind, and urge him to take some time off. Hanna and Deeks intercept the two NSA analysts as they're trying to escape town, with guns, burner phones and a bag of cash in their trunk. Outside the hospital, Kensi stands up out of her wheelchair, but falls when she tries to walk. Carter says the cartel was after Townsend and Larsen because they had embezzled funds from it, and Dill inadvertently helped them do it. Two cartel thugs abduct Callen from the hospital, after he switches wristbands with Dill. Callen is loaded onto a boat and taken out into the ocean, to interrogate him with the threat of feeding him to a shark. Hanna and a SEAL team buddy, Tom Olsen, head out after them. Callen is pulled under, by Hanna, and comes up shooting. Callen tells Dill that he's safe. Deeks finds Kensi feeling sorry for herself, and Deeks tries to propose again, but Kensi waves him off, refusing to consider it while she's in a wheelchair. Owen tells Hetty he's dyng from the effects of Agent Orange.