Annie's sister Danielle decides to take her daughter's class on a field trip to the Smithsonian Institute. The only problem is that Annie doesn't actually work there; it's just a cover for her real job at the CIA.
Meanwhile, DPD has its sights on a pharmacist, Don Ridley, who has been a major conduit for an Angolan diamond smuggling ring from the UK to the U.S. After the FBI captures Ridley at an airport, Joan wants to keep the smuggling ring going so they can find out who is masterminding the operation. Now, Annie and Jai must pack their bags for London.
Annie meets with Vivian Long, a suspicious U.S. embassy worker who allegedly used Ridley to grease the rails of the diamond smuggling operation. Using her cover as a museum art dealer with a gambling problem, Annie gets in to the famous Havery casino room.
All the while, Jai monitors Annie's every step from a secret communications house. Together with the CIA's UK field operative, Jai goes to check out the diamond transfer house, but they soon find themselves dodging bullets instead of finding answers.
Back at the casino, Annie is losing money at the craps table and Vivian is worried. Annie decides to place all her money on one single bet. Will the CIA operation go bust or hit the jackpot?