What could a computer wizard self-exiled in an abandoned Buddhist temple possibly have in common with the humble servant of a medieval fresco painter? What is the link between the enigmatic mission of a giant radio-telescope and a tribe of spherical beings who dwell in a world full of unearthly scents and herbs? What will bring four great scientists from various centuries, Archimedes, Ludolph van Ceulen, Nikola Tesla and Stephen Hawking, to the same spot in time? What has this got to do with Rama, a female computer program, impregnated by a strange ape? And, above all, why is it necessary for Sherlock Holmes and Moriarty to join forces so that the Fourth Circle can finally be closed?