The British spy agency MI5 recruited Willie Carlin to infiltrate Sinn Fein in Northern Ireland. He spied on the group for 11 years until his cover was blown.   Check out I Spy's merch by going to https://store.dftba.com/collections/i-spy Save 15% on FP subscriptions. Visit https://foreignpolicy.com/subscribe/ and enter code ISPY at checkout to claim this offer.