The hero is Peter Landers, an officer in the merchant navy with a drink problem following divorce. After a prison sentence he is offered a 'last chance' opportunity to carry out an undercover assignment; if successful he may be reinstated with his previous employer. He is to sign on with a scruffy cargo boat, the Turkish Slave, suspected of smuggling operations, and try to collect evidence of who is involved and where the loot is delivered.
However, the crew of the Turkish Slave grow suspicious and, just as they are making a rendezvous off an island on the coast of Brazil, Peter is thrown overboard. He survives the long swim to shore, is befriended by a peasant girl (who turns out to be the daughter of the island's chief citizen), discovers who the villains are, and survives a tidal wave (we would say tsunami, but the term was not in wide use then) brought about by the eruption of the island's volcano. We presume he will get his job back.
This was Canning's seventh post-war book for Hodder and Stoughton, published in 1954 at 10/6 with a print run of 14,000 copies and with a simultaneous cheap book club edition at 6/-. It first appeared as a supplement to the Toronto Star Weekly on 14th November 1953 under the title "Trial by Water", and was also serialised in John Bull, December 1953/January 1954, with some vivid illustrations by S. Fancett shown below. The US edition by W. Sloane Associates came out in 1954. There was a 1961 paperback at 2/6 with a print run of 25,000. It was included in the Heinemann Uniform Edition of 1970; a later report to Hodder and Stoughton showed 521 copies sold in that form. In 1957 a comic strip version under the title "The Jewel Smugglers" was issued in Super Detective Library No 95, and has been reissued together with Oasis of Mystery by Lulu.com.
Happily there is now a new edition from Bello, the "modern classics" imprint of Pan Macmillan.
The lengthy and very vivid account of the swim to shore, occupying pages 14 to 22 of the hardback edition, recalls Canning's previous use of a "trial by water" in his Alan Gould novel Atlantic Company published in 1940, which describes life in an open boat adrift in the Atlantic after the torpedoing of a cargo boat.