It was the ultimate cold case. The murders occurred on Mars twenty years ago, so how can Detective Inspector Richardson, a local policeman from Melbourne, Australia, track down the murderer - and why is he being asked to? Twenty years ago, the Prometheus landed in the Hellas Basin on Mars and all the crew died from unknown causes. When an historic site survey crew arrive, they find that the circumstances of the deaths weird and inexplicable. Yet secret coded instructions from the UN space agency HQ on Earth indicates that these circumstances were somehow known in advance. This is murder and Detective Inspector Richardson, a local detective from Melbourne, is called in to solve the case. There are only four people with means and opportunity, all of them are highly focused, very intelligent and none of them, apparently, has a convincing motive. Richardson must sort out their stories to find the guilty, all the time wondering why he was given this job at all.