An American spy - Olen Steinhauer

Milo Weaver is still haunted by his last job. As an expert assassin for
the Department of Tourism, an ultra-secret group of super-spooks buried
deep in the corridors of the CIA, he fought to keep himself sane in a
paranoid and amoral profession. Now, the Department has been destroyed,
and with it Weaver's livelihood. Finally he can spend time with his
family - without constantly looking over his shoulder and fixing one eye
on the exits.
Weaver's former boss is not so settled. For Alan
Drummond, Tourism was everything. Now, all he wants is to take revenge
on the Chinese spymaster that exploded their operations from within.
Weaver tries to persuade him to leave sleeping cells lie, but when
Drummond disappears from a London hotel room, Weaver is sucked back down into
his old life. Soon, Weaver is sifting
through secrets, lies and misinformation. If his time as a Tourist has taught
him anything, it's that nothing and no-one can be trusted - even within
the CIA itself...