[1] Marsh biographer Joanne Drayton[2] relates how the writer based the novel's Cape Farewell on a lengthy 1954 sea voyage she took aboard the Norwegian ship Temeraire, with a cargo of wool and 10 passengers, from Adelaide to Odessa, touching in Spain before its ultimate docking in Wales.

Two actual wartime cases clearly provide reference points for her plot - those of Gordon Cummins London's 'Blackout Ripper' and Eddie Leonski Melbourne's 'Brownout Killer'.

[citation needed] Shortly before the midnight sailing of the cargo ship Cape Farewell from the Pool of London, bound for Cape Town, with its crew and full complement of 9 assorted passengers, the body of a strangled woman is discovered on the fog-wreathed dock, clearly the third victim of a serial killer who scatters flowers and broken beads on his victims and sings as he departs.

Scotland Yard Superintendent Roderick Alleyn boards by pilot off Portsmouth and poses as a passenger with the aim of identifying the culprit and preventing another murder on voyage, despite the grudging co-operation of the ship's Captain Bannerman, whose obstruction and denial of the situation enables a further killing to take place on voyage.

The passengers are a very mixed collection - a glamorous socialite widow, a sweet young girl who's been jilted at the altar, a deeply unhappy middle-aged spinster with a specialism in church music, an Anglo-Catholic priest, a pedantically tetchy school-teacher, an alcoholic TV presenter on the edge of a nervous breakdown, a charmlessly smug middle-aged couple and an eccentric elderly bachelor.