The Interloper — John Russell Fearn

Warfare between Earth, Venus and Mars is brewing, their hates being fanned by the sinister intrigues of a power-drunk armament baron, Chester Candris. Candrris is enamoured of Ann Urslor, the fiancée of a government official, Ken Hargraves. When Hargraves departs into deep space on a secret mission to prevent the impending war, he is followed by Candris who shoots him, disposing of his rival. But some time later, a gigantic face in the depths of space appears in the night skies on Earth, apparently watching over the planet...and gradually moving nearer. The press dubs the face 'the Interloper' and humanity watches in superstitious awe... then the Interloper speaks!