A pilot replacement for 633 Squadron named Chalmont puzzles Frank Adams, the station’s intelligence officer. Why should a sensitive young poet volunteer to join a squadron with a war-like reputation? Chalmont is teamed up with Richards and both show high skill and courage but when ordered on a mission which may involve the death of many civilians both airmen refuse to take part. Now they must face court-martial.
Although Operation Safeguard was the last book written in the 633 Squadron series, the events in the story take place immediately after those in Operation Valkyrie.