Golden Gate (City Spies Book 2)

From the publisher: "After thwarting a notorious villain at an eco-summit in Paris, the City Spies are gearing up for their next mission. Operating out of a base in Scotland, this secret team of young agents working for the British Secret Intelligence Service's MI6 division have honed their unique skills, such as sleight of hand, breaking and entering, observation, and explosives. All of these allow them to go places in the world of espionage where adults can't. Meanwhile, there's been some new intel regarding a potential mole within the organization, offering the spies a lead that takes them to San Francisco, California. But as they investigate a spy who died at the Botanical Gardens, they discover that they are also being investigated. And soon, they're caught up in an exciting adventure filled with rogue missions and double agents!"