On February 17 and 18, 1944 American carrier-based planes attacked the Japanese fortress at Truk Lagoon, in the western Pacific Ocean. Bombs and torpedoes sank more than 40 ships and over 200 Japanese fighter planes were destroyed. 50 years after Operation Hailstone, a Canadian film crew visited the lagoon to document the sunken ships. The program climaxes with the search for the Katsuragisan Maru, the last of Truk's long-lost shipwrecks.