Philip Shane, journalist for the London Sunday Sentinel and undercover agent for the British Government, sets out, at the Prime Minister's request, to investigate the death of key scientists on the moon. His fellow travellers are Claire Scott, daughter of Sir Fabian Scott, pioneer of Lunar City; Professor Denis Quarles, a one-man Investigating Commission; Gaff Midley, a psychiatrist; the Ferry Rocket Commander and crew.

At Woomera, firing base for the Ferry Rockets in the year AD 2050, Shane is drugged and sabotage occurs. On the Commonwealth Space Station, 1079 miles above the Earth the Ferry Rocket Commander is killed.

Who is responsible, and why?