When Nick and Sally's boat sinks, they need to build another boat, but don't know how. A trip to Floating Island helps them discover that, along with needing the right material, you also need to make the shape of your boat float. Nick is in pursuit of finding out how to build a drawbridge. In Spansylvania, they meet a dragon who chases after them - and along the way they find out that some materials are better suited for bridges than others.