Mary March had been having some murderous thoughts as she walked through the Great Park in Windsor early that October morning. So perhaps it was fate that she should find the first victim . . .
For only a few hours later, in the recently abandoned home of her neighbour Alice Hardy, Mary discovers the body of a young man, his face painted red, white and blue - his thymus gland expertly cut from his chest.
And for high-ranking policewoman Charmian Daniels, brought in to head the investigation, this is just one of a number of disturbing features. Because the thymus gland in animals is known as the sweetbread, an edible delicacy - and Mary has received a note which claims this murder is just a 'taster'.
But is Mary all she seems? Is she the persecuted or, in fact, the persecutor? And why has Alice Hardy disappeared? Has she become another victim - or could she be the murderer?
As Charmian seeks the answers to these questions, the killer has more work to do . . .