Scorpion Deception (Scorpion Novels, 4)

Ex-CIA and now freelance agent Scorpion hunts a faceless enemy—a mysterious Iranian known only as “the Gardener”—in Andrew Kaplan's Scorpion Deception, the electrifying third installment of the espionage series that Suspense magazine says “matches the best of Ludlum, and then surpasses it.”
 
Files containing highly classified information on CIA assets have been stolen from the U.S. embassy in Switzerland by a well-armed and well-trained hit squad.

Under intense political pressure to find those who orchestrated the attack, the CIA turns to the deadliest agent they know: Scorpion. But Scorpion is unwilling to get involved...until he learns his name is at the top of the stolen list.

Scorpion, a strong, intelligent, and lethal action hero, must travel to Iran to hunt down “the Gardener” before an all-out war erupts in this sensational spy thriller.