Mary Russell is well used to dark secrets - her own, and those of her famous partner and husband, Sherlock Holmes. Trust is a thing slowly given, but over the course of a decade together, the two have forged an indissoluble bond. But what of the other person Mary Russell has opened her heart to, that third member of the Holmes household: Mrs Hudson? Russell has come to love - and trust - the long-time housekeeper like the mother she lost so long ago. Mrs Hudson, once the most long-suffering landlady in all of London, followed Holmes into his Sussex retirement back in 1903. Surely she had good reasons for that? Russell has never questioned why, until a man comes to the door one morning, claiming to be Mrs Hudson's son. What Samuel Hudson tells Russell shatters her childish faith. It cannot possibly be true, yet she believes him. She also believes his threats: both the gun in his hand, and the knowledge he holds.