The ever-complaining Brenda Balderdash and her long-suffering husband Bernard return to Sunnysands and stay at the Mill. They arrange to hire a boat and mistakenly take Bob's boat out to sea. Little do they know that Grandpa has stowed away on board.

Before long they are heading to rocky Bongle Island. Grandpa is desperate to make them turn back so he hides behind the radio and issues a warning to all shipping in the Bongle Island area - there are sharks about! Brenda immediately insists that Bernard turns round and goes back to Sunnysands Harbour. But how can Grandpa get off Bob's boat? Luckily, Josh and Elsie see his signal and persuade Auntie Jules to go and collect the Balderdashes, and Grandpa of course. It's teamwork! Show less