The Night Manager By John le Carré

At the start of it all, Jonathan Pine is merely the night manager at a luxury hotel. But when a single attempt to pass on information to the British authorities - about an international businessman at the hotel with suspicious dealings - backfires terribly, and people close to Pine begin to die, he commits himself to a battle against powerful forces he cannot begin to imagine.
In a chilling tale of corrupt intelligence agencies, billion-dollar price tags and the truth of the brutal arms trade, John le Carré creates a claustrophobic world in which no one can be trusted.