Mac must deal with a potentially deadly situation when she learns that terrorists have smuggled explosives across the Canadian border. Mac's course of action conflicts with the Attorney General's, and Templeton enjoys being able to publicly second guess Mac. Meanwhile, Amy is sad to learn that she'll have to have a Halloween party instead of trick-or-treating, due to security concerns, and Horace has a hard time dealing with Rod being poked fun at for being First Gentleman.