Charles Lenox, Victorian gentleman and armchair explorer, likes nothing more than to relax in his private study with a cup of tea, a roaring fire and a good book. But when his lifelong friend Lady Jane asks for his help, Lenox cannot resist the chance to unravel a mystery.

Prudence Smith, one of Jane's former servants, is dead of an apparent suicide. But Lenox suspects something far more sinister: murder, by a rare and deadly poison. The grand house where the girl worked is full of suspects, and though Prue had dabbled with the hearts of more than a few men, Lenox is baffled by the motive for the girl's death.

When another body turns up during the London season's most fashionable ball, Lenox must untangle a web of loyalties and animosities. Was it jealousy that killed Prudence Smith? Or was it something else entirely? And can Lenox find the answer before the killer strikes again-this time, disturbingly close to home?