The Pearls Of Lutra by Brian Jacques

This is ninth thrilling "Redwall" adventure - new in paperback! Far away, on the isle of Sampetra, Emperor Ublaz - also scarily known as...Mad Eyes - sends his fearsome lizards and seascum on a murderous mission to Redwall. Meanwhile Tansy and her fellow abbey dwellers frantically race against time to unravel a fiendishly difficult set of riddles and rhymes left by the Fermald the Ancient...