With a view to escaping both boredom as a junior G.P. and unwanted womanly advances, young doctor Simon Sparrow becomes a medical officer on the Lotus, an all-male cargo ship.  As soon as he sets foot on board, Simon encounters various eccentric characters (including quick-tempered, authoritarian, whisky-addicted captain Hogg) and gets involved in many an embarrassing situation (including seasickness).

In Rio he gets to know Hélène Colbert, a sexy young French singer and falls under her spell.  When woman hater Hogg is forced to take on two female characters, Muriel Mallet, the daughter of the shipping company and her friend, Hélène, on his freighter, Simon is delighted.