When a lively group of schoolfriends embark on a ferry trip across the River Mersey, they expect to arrive at Liverpool but somehow end up on the shores of Egypt! Can it be that half of a strange green stone recently found by one of the children has got something to do with this mysterious voyage?

The group unwittingly are drawn into a dangerous adventure centred round an archaeological dig at the Great Pyramid. The tomb of an ancient god in the pyramid must not be disturbed, or disaster will hit the world. But the evil Doctor Gwendolyne Deeath, an archaeologist at the site, has special plans. And she has the other half of the green stone.

Will the most terrible horrors be unleashed on the earth or will the children's courage and friendship be strong enough to resist the treacherous Doctor?