Every year when the harvest moon shines, families of noisy Cockney hop-pickers descend on the bountiful countryside near the village of Plummergen, home to Miss Emily Seeton, artist and Scotland Yard aide extraordinaire.

But the holiday jollity brings no cheer for local police Superintendent Brinton, who is all too aware it's a whole year since the gruesome "Blonde in the Bag" murder, and they are still no nearer a solution.

Will Miss S be asked to set aside her newfound hobby of gardening and lend a hand? And where in her strange sketches of the Last Night of the Proms are the clues that might identify a brutal killer?

Serene amidst every kind of skulduggery, this eccentric English spinster steps in where Scotland Yard stumbles, armed with nothing more than her sketchpad and umbrella!