August 1911. Emily Hardcastle and her inimitable lady's maid Florence Armstrong are enjoying a fine summer until Harry, Lady H's brother, turns up out of the blue with a mystery for them to solve.

A routine parachute test at a local aeroplane factory has gone horribly wrong--with pilot Dickie Dupree plummeting to his death. Harry is certain there is more to this 'tragic accident' than meets the eye, having discovered that someone at the airfield is leaking top secret intelligence to foreign rivals.

In between strolls to the Dog & Duck and planning for the annual village show, the daring duo dust off the Crime Board and go undercover at Bristol Aviation. With international powers investing heavily in aeronautics, the stakes are high--sky high--and the suspects soon mount up.

Can Lady Hardcastle find the culprit before someone else falls down dead?