Tension grows, however, over the presence of an alien spaceship that is orbiting the world, bearing a single occupant - the Sigman. It appears that no-one knows how to communicate with the Sigman; no-one knows the purpose of his visit. Until two people - one "straight" and the other a Byworlder - solve the problems involved; and in so doing trigger off a series of violent plots and counterplots that mount to a frenetic climax.