After Mary hid her treasure, it is unknown what happens to her. Mary had visited Smuggler's Cove probably to stock up on supplies, like food, and to hide the treasure. Nobody knew her secret then, but it was revealed at some point, as there is a whole museum exhibit about her, including a picture of her as a teenager, not to mention a drawing of her in the shed. Mary Pierce also dressed as a man, going by just the name 'Pierce,' and wearing a fake mustache. Additionally, in the well on the island in the game, (where the treasure was in the book) Mary writes that her treasure is not there, showing that she knew about the treasure in there beforehand, possibly leaving it there first, then moving it once it had been found. It is also possible that Mary's treasure is the one you find in the I Spy Treasure Hunt book, as the phrase 'Think of me' is found both in the cave in the book, and by her treasure in the game. is the second/third pirate whose treasure you have to find in I Spy Treasure Hunt.
