Twinkle, Twinkle, Little Spy // Catch a Falling Spy — Len Deighton

When the unnamed British agent in this story is sent to take custody of a defecting Russian scientist, his mission takes him to the Arab world and the Sahara desert as he is consistently foiled by a US Secret Service high-up. Loyalty is tested and never certain, as it becomes unclear as the novel develops who is actually chasing whom, and where the threat is coming from.