Danny's taking the subway home after a long shift, looks out the window and sees a body lying on the tracks. He gets the train to stop in time, but discovers, along with Mac who arrives in tuxedo (from a Mayor's reception) and Lyndsay in a gown with a boobs hanging out (from a night at the opera) that the man is dead. It looks like he was "subway surfing," meaning standing on top of a speeding rail car through the subway.
Once the ME examines him, however, it's a different story. It appears he didn't die from injuries falling of a speeding rail car, and there are strange small fishes in his stomach as well as a shark tooth that totally through one of his hands. What's with all this?
Story number has Don and Stella finding a well-known stock broker hanging from the end of a noose outside his high-rise window. Once again, the ME report shows he didn't kill himself; that he was strangled and asphyxiated. Sheldon joins the other two on the case.
Neither conclusion was anything that interesting, at least not to match the beginnings of each story.