The human race is in decline, is withdrawing into protective city shells. Could contact with civilised aliens revive the probing curiosity once the hallmark of human achievement? Are there any such beings in the Universe? If there are, can they be contacted?

The beginnings of an answer, oddly enough, begins to form when Alex Craven sets out in search of his girlfriend Nicole and finds her working in the marshlands of the Angles. Reluctantly he becomes involved in her work. She is experimenting with empathic communication between twins. Eventually, accompanied by one of two particularly gifted twins, he leaves Earth for New Carthage.

In that strange world a shadow-line civilisation is in perpetual slow motion to avoid the intolerable daytime heat. But what lies beyond the shadow line . . . ?