Will returns to San Francisco to sort out his finances after a surprising royalty check. Andy reveals to him that his wife Laurie might be pregnant and he needs Will's help to find out. Meanwhile, Marcus's new "friends" don't sit well with Will and he attempts to convince Fiona that the kids are up to no good.

Will throws his annual Halloween bash, much to the dismay of Fiona and Marcus, who consider it one of their least favorite holidays. Despite the fact that Fiona believes Will has other motives for throwing the party, she ends up meeting Sean there and reveals a whole new side of herself. After a few mishaps at the party, Will shows Marcus the joys of Halloween.