After breaking up with Robin last week, Barney is back on the "dating" scene and breaks out his old Playbook. We meet up with Barney at McLaren's dressed in a SCUBA suit about to use his moves on a hot chick sitting at the bar. Robin reveals she's a little heart broken over how quickly he's moving on and Lily goes to warn her what a jerk he is and she joins the gang as Lily catches her up on the story: We get to see a series of elaborate gimmicks that Barney uses out of the old book and believe us, they work for him. Lily gets annoyed that she knows how nice Barney can be, yet still uses deceit. The final straw is when Barney uses a trick of his on a girl that Lily was trying to set Ted up with... for three years. Lily then hires an actress to "fall" for one of Barney's tricks and steal the Playbook.
We catch back up to the present with Barney in the SCUBA suit and the girl, Claire, asks why they don't just go up and ask Barney about the suit. They do, and Barney starts doing the routine and then gives up and feels guilty for moving on from Robin so quickly. The gang convinces Claire to just grab coffee with the honest Barney. When she leaves, Barney tells them to check under the table where they find the missing page of the playbook... the SCUBA diver. It's all an elaborate scehme that included getting Lily to steal the book. The suit? A red herring. Well done and well executed.
Meanwhile, when Robin claims she was just going to focus on work and not dating, Ted and Marshall tried to convince her that means she was gonna fall in love. She doesn't believe them until she meets her new hunky co-anchor at work after the credits.