Shawn and Gus are at a restaurant having lunch, or more like breakfast in Shawn's case, who is eating cereal in an attempt to break the "Breakfast Served Until" barriers. As Shawn launches into his usual flirting routine with the waitress, Gus calls him on never taking relationships seriously. So Shawn, in an effort to prove him wrong, calls Abigail Lytar, his high school crush he reconnected with at his reunion, and asks her on a proper date. The guys are then summoned down to the police station. The Yin Yang Killer, a serial killer who was active when Henry was a cop then went silent, is back and wants to toy with the department again, this time singling out Shawn as his primary playmate. Mary Lightly, the police profiler, explains that Mr. Yang challenges the cops with the opportunity to save his victims by solving his riddles. Yang has just sent them another one, along with a stopwatch. They have an hour and ten minutes to solve the riddle and save his latest victim. Henry storms into the station, having heard that Mr. Yang is back and has set his sights on his son. He forbids Shawn to get involved with the case, explaining that if Yang has targeted him, he has also targeted the people he loves. But someone's life is in danger and Shawn has no choice but to play along. He figures out the riddle and is shocked to discover the target is the waitress he was flirting with earlier. They all arrive at the restaurant to find the waitress missing and a yin yang symbol with a streak of blood on her locker. Yang has left them another riddle and a stopwatch, this time giving them only eighteen minutes. Shawn realizes their next location is the police station, and he heads back to find Madeleine there waiting for him. She reiterates Henry's concerns, but Shawn tells his mom he's got this one and will wrap it up in time for his date with Abigail. Madeleine hopes he's right and wishes him luck.