In August 1483 two boys are inside the Tower of London, shut in there by their uncle, King Richard III, known for his kindness and justice.
Meanwhile, in faraway south-west France, Belina Lansac is selling medallions and statues to pilgrims visiting her local cathedral, unaware that the fate of the two boys is in her hands. Belina's husband William is the town's detective and he has just been ordered to investigate the death of a poisoned pilgrim. Belina's normal life vanishes as her husband leaves home on a secret mission. Now Belina must be the detective and work all alone without the protection of her husband.
She diligently investigates poisonous plants, food and drink but she is a reluctant and squeamish sleuth. So she welcomes the help and attention of Philippe Barvaux, her new neighbour, unaware that he is an unscrupulous and ambitious lawyer who had been ordered to kill the Princes in the Tower so that false rumours may be spread in England against Richard III.
Philippe has already committed the ultimate crime: the murder of two innocents he mistook for the princes. He is unaware that he has sacrificed the wrong victims until orders arrive telling him to murder the real princes as they are smuggled to safety through France to Portugal. Belina learns about these new orders, and searches for a last desperate chance to save the two princes.
Will the princes reach safety? Will Philippe manage to drown them this time? Can Belina save them and indeed survive herself?