When a vital CIA hard drive goes missing, Steven and Samantha must travel to Dublin, Ireland in search of a prisoner who holds the key to its location. Following leads, their mission takes them to England. Meanwhile, Samantha begins to question whether or not she and Steven should speak about their pasts, and Lizzy invests time and money in the catering business.

Steven and Samantha are to find Shin Won—a North Korean physicist responsible for inventing a device that can change an object's state of matter—and facilitate his defection. What should be an easy mission in Geneva, Switzerland becomes more complicated by the minute when Shin Won refuses to come to the U.S. unless they get his daughter out of North Korea. Meanwhile, Samantha misses Lizzy's milestone celebration.