Mr. Cave is an antique shop owner with some curious items in his collection. One of these if an extraordinary crystal egg, which he comes across one evening. Indeed, the egg seems to be a gateway to the planet Mars. This science fiction short story by H. G. Wells dating back to the late 19th century has inspired numerous other literary pieces, as well as radio and television adaptations. "The Crystal Egg" is considered to be a precursor to H. G. Wells' famous science fiction novel "The War of the Worlds" from 1898.