At first it seems the Great Fog has claimed another victim. A drunk, perhaps, wandering unsighted through Hyde Park and stumbling into the icy shallows of Long Water.
But Max Stensness was stone-cold sober when he died. And in the hours before his death, the young biochemist had claimed to be in possession of a secret that could change the world.
Having traded MI5 for New Scotland Yard, Detective Inspector Herbert Smith thinks he's left the murky world of espionage behind him - until he begins retracing the final footsteps of Max Stensness.
Suddenly he's being tailed, thinly veiled threats are issued, danger lurks at every turn in the investigation.
The CIA, KGB and MI5 are all vying to get their hands on the dead man's secret, and as the body count climbs, it's clear someone will stop at nothing to claim it.