As Piper prepares to go on a business trip to Hawaii, she worries about how Prue and Phoebe will handle any magical crisis that might come up while she's gone. Meanwhile, Phoebe goes on a sight-seeing trip to Alcatraz, where she comes across a spirit. It takes possession of a security guard, in order to make his way across the water and seek revenge on the people who were behind his conviction. As a result, Phoebe and Prue have to find a way to banish the spirit before it's too late.