Cantankerous old Captain Shannon feels hardly blessed when scientist Martha (""Frozen"") North is piped aboard his Fishery Protection Cruiser, the Martin. Their mutual mission is to track down a reported sea monster (the last of the plesiosaurs yet) and in the meantime they run into a shoal of smugglers, hijackers and, of course, the legend of the lost treasure ship. So many red herrings, so little meat.