Hannah Montana boards the ship, and Cody promises Bailey he can get them tickets to her concert in Hawaii. Meanwhile, Alex, Justin and Max Russo enjoy a teen cruise---until Alex pulls a prank on Justin that literally makes him blue.
Zack befriends a cranky passenger (Gavin MacLeod) and teaches him how to pull pranks on the other senior citizens on the ship; London plans a trip into space and searches for the right companion to go with her.
The boys plan to celebrate their birthday with their dad, but a surprise visit from their mom disrupts the all-guys weekend. Worse, the twins fear their parents might stay on the ship for an extended visit. Meanwhile, London tries to find the perfect belated birthday gift for Mr. Moseby.
The ship docks near Rome and London falls for a handsome street musician, but Bailey learns that the young man's motives aren't entirely pure. Meanwhile, Zack and Cody concoct a plan to become chefs so they can eat at a famous Italian restaurant.
Maddie (Ashley Tisdale) visits the crew in Europe and wins the heart of a young prince who insists on marrying her---or else she will be imprisoned and the ship won't be allowed to leave port. But the boys concoct a plan to get everyone free.