The story is told in 1903 of an event in 1883. A gem in missing, the Epiphany Emerald. There are twelve people sharing a dinner on twelfth night at the Oliver's house, including Holmes and Watson. One of them took the gem. Was it Grandmother Oliver, a kleptomaniac, or either Mr. or Mrs. Barnaby Oliver, or Antonia, the 8 year old daughter, Andrew, the 20 year old son with gambling debts, Sebastian the eldest son, Olivia the elder daughter or her husband Valentine Feste, or the music hall creature on the arm of Sebastian, Viola DeVere, or her unknown friend? Surely it couldn't be Watson or Sherlock Holmes who rounded out the twelve. It wasn't Maria the maid or Fabian the butler, nor was it the ginger cat or Curio the monkey.