A desperate letter from his grandfather prompts Patrick McWaid and his family to return to Boomerang Bend, where the Lady Elisabeth still rests on the bottom of the river. But they arrive to find the Old Man crushed by many setbacks. Not only has his entire crew left him, but the money meant for repairs has disappeared!

With no other choice, the Old Man has sold half the boat to a mysterious investor in Goolwa at the mouth of the Murray River. But there's one catch he must deliver the paddle steamer to her new half owner in thirty days or lose his remaining half! It's a long way to Goolwa, and first they must raise the Lade E from the river bottom. Can the McWaids make the necessary repairs in time?