A classic Irish children's book, still a best seller after more than thirty years. Conor, his younger brother and two of his friends adventure to a local island in his father's boat. While there, they unknowingly uncover a secret that has been kept for over two thousand years. But Lady Agnes and her husband, the Captain, have discovered the secret as well and they will stop at nothing to keep it to themselves, even if it means trapping the children on the island for ever...