Detective-Sergeant Martin christened him 'Whiskers', but nobody could be certain who he really was. That was not the only question that confronted Inspector Charlton of the C.I.D. How, for instance, did young Courtenay Harbord die? And why? Who was Number 106 and in what way did Mr. Ninian McCullough upset the apple-cart?

The fourth Duke of Redbourn had built Etchworth Tower on the summit of High Down in 1782 and it was at the foot of it that they found Harbord one autumn morning, falsebearded and with a broken neck. It looked, on the face of it, a simple case of suicide, but was it?

A delicately-handled love affair adds piquancy to the complicated, but never tedious, investigation; Sergeant Bert Martin is always there with his pungent Cockney wit; and from the moment when old Tom Lee says, 'Well I'll be danged!' the tale goes steadily forward to its exciting climax.