The five grandchildren often stayed with Granny in a house by the sea. One day they drove to the harbor to see the boats sail past, and Granny knew they were secretly wishing they had a boat of their own. Off to the London boat show they went and found two boat builders perched on a lovely wooden boat. Granny asked if they could build a boat for the grandchildren, and this is where the magical tale of Sarky Puddleboat began. There is something mysterious and magical about Sarky Puddleboat, however. Sometimes the portholes look like eyes, and the stern appears more like a tail than the back of a boat. The children are eager for adventure, but when they break Granny's rule and leave the safety of the harbor, they find themselves in a much bigger adventure than they bargained for. Will Granny's magic rescue the desperate sailors in time?