Archangel (1982)
Archangel tells to story of a mechanical engineer called Michael Holly who is approached by British Intelligence to do some errands for them on his business trips to Russia. He gets caught in the act and is sent to a labour camp in the Arctic circle. There he refuses to give in and earns the respect of his fellow prisoners, even leading a prison revolt.
This may all sound cliched, but it isn't. It is a great novel with well drawn characters. This book remains one of my all-time favourite Gerald Seymour novels.