It is a locked room mystery or, more properly, a subset of that category known as an "impossible crime", and features the series detective Sir Henry Merrivale.

It comes from a tomb that Helen and her father, Lord Severn, helped excavate.

In defiance of the dire predictions of an Egyptian soothsayer, she brings the lamp back to Severn Hall, her ancestral home in England.

At the door, Helen stepped out of the car, leaving her friends to follow her into the Hall.

On the floor, in the middle of the vast entrance hall, were her coat and the bronze lamp.