\'Dan and Prudence Weldon, the terrible twins, were always looking for trouble--sometimes, they deliberately went over the weir in their canoe--just for the fun of it! Rowan Berry, their friend, was on the other hand, much quieter and more thoughtful. Meeting at Micky Shuvellin\'s, the Irish lock-keeper, who beguiled them with tales of his past adventures, they discussed the Riddle of the River and made up their minds to solve it for themselves.\' Published in 1946, this is a great tale for young readers, ideally pre-teen readers. The spine is a little worn but the pages are easy to read.