Kolymsky Heights by Lionel Davidson

Kolymsky Heights. A frozen Siberian hell lost in endless night. The perfect location for an underground Russian research station. It's a place so secret it doesn't officially exist; once there, the scientists are forbidden to leave. But one scientist is desperate to get a message to the outside world. So desperate, he sends a plea across the wilderness to the West in order to summon the one man alive who can achieve the impossible...