The Crusader's Treasure

As they follow Sir Hugo's clues the children discover a secret passage hidden in the wall shaft which leads them to the much sought after crusader's treasure. They accidentally discover a secret door in the treasure chamber which leads into Blaize Castle but they are again surprised by the gamekeeper, who lock them and Sir Hugo in a dungeon while they themselves start to take the treasure down to a boat. There is a passage from the dungeon to the sea and the tide is rising dangerously.