Bombay, 1909. Genevieve Masefield and George Dillman make a living as detectives aboard the early twentieth century's most extravagant ocean liners. From the members of first class in all their finery, to the card cheats and pickpockets plying their trade, they've experienced more than their share of humanity.

For their latest voyage, the Salsette boasts a pair of travellers who feign ignorance of each other but there is clearly no love lost between them. Then there’s an elderly man whose powers of deduction may be based on more earthly techniques than the mystical energy he claims to possess. And there's a young woman and her mother who find their way into the middle of every bit of trouble aboard. The lives of this group of travellers are set to intersect in ways none of them could have foreseen on dry land – including in a murder.