Sherlock and Mycroft work together when Joan is taken as collateral. It becomes a race against time when they only have 48 hours to deliver a man and a list a names to free her. When the man they're searching for turns up dead, they find the man who killed him.
Mycroft proves to be who he hasn't claimed to be when he tazers Sherlock and goes to Joan on his own. Just as all looks as it may not fall through, Mycroft and Joan are swarmed by British agents.