An under-the-weather Sherlock investigates the murder of a college professor whose body was found with gunshot wounds through both of his eyes. Using his trademark deductive reasoning, Sherlock retraces the victim's path back to an illicit gambling parlor in Chinatown where he was shot. Gregson is able to bring in the gunman thanks to video surveillance footage, but when the killer claims that he was hired to take out the professor, Sherlock realizes that his work has only just begun. Meanwhile, Watson gets a call from an addict and former lover who is in prison and needs her help.
