Helen and Ridley Ambrose are preparing to set off for an exotic resort off the coast of South America on the Euphrosyne, a ship belonging to Helen’s brother-in-law Willoughby Vinrace. Travelling with them is his daughter Rachel – a quiet, unremarkable girl raised in the London suburbs by her spinster aunts after the death of her mother. Along the way other people come aboard, such as the upper-class Clarissa and Richard Dalloway and the scholar William Pepper. As Rachel interacts with the other passengers, intrigued by their different personalities, it becomes clear that what started for her as a mere sea voyage is turning into a journey of self-discovery and a rite of passage that will change her for ever.