Two brothers watch a ghost ship sail along the river towards the sea, one Halloween night. They suddenly find themselves enveloped in fog, before being deposited on the deck of the ship. They later learn from the crew that they have no hope of escape. When the ship trades goods with the Bobbup Island, the chief refuses to let the boys go. However, after getting help from the boys, the inhabitants of the island set them in the direction that should lead them towards home. There are many dangers ahead for them, not least when they fall foul of the deadly blowpipes of the Grenhogs of Gremable Island. Later they once again see the ghost ship, and fall in danger of being spotted by the captain, and being returned to his clutches. Can they survive the perils facing them and reach the safety of their home? Can they evade being captured or will they never escape? That is for you to find out.