When Ben decides to throw a birthday party for Kate against her wishes, her frustration soon turns into excitement when she realizes that Ben invited Molly, Kate's wild friend from high school, to her party. Meanwhile, Ben finds out that Darcy, the only woman he truly cared for, is moving into what used to be his and Darcy's dream home with her new husband, and Tommy comes clean to Kate about why he hates Molly.

Kate gets invited to her hot neighbor's Halloween party, so BJ tries to help Kate break free and be someone completely out-of-character for the night. Meanwhile, Ben and Tommy decide to stay home and hand out candy to the trick-or-treaters in hopes that they'll meet some hot moms, but the night takes a turn when Tommy unknowingly eats some of BJ's "candy" from Amsterdam, and Kate bonds with Will (guest star Stults), a single father.