As a joke, Sheldon and Penny try an experiment designed to make participants fall in love. Also, Leonard, Amy, Raj and Emily spend the evening trying to escape a room with a 'zombie.' Bernadette and Howard run into trouble at the airport.
When diplomatic immunity complicates a child abuse case for Danny and Baez, Frank intervenes despite not having jurisdiction on the case. Also, a robbery occurs while Eddie and Jamie are on a double date with Eddie's boyfriend and his sister.