Our trip home became interesting on the second leg - Seattle to Houston. About 45 minutes out strange things began to happen. One of the flight atendants sat in a vacant chair and started stopming on the floor. Then a Continental Captain who was dead heading on the flight started laying on the floor with his ear to the ground and tapping with his fist. Somehow they came to the conclusion that somebody was trapped in the baggage compartment. So we turned around to return to Seattle. We were marshalled out to a vacant piece of tarmac and surrounded by official looking vehicles. The Seattle police, TSA and Port of Seattle were well represented. It turned out there was nobody in the baggage compartment. They decided to take all the bags out anyway and get their bomb dogs to sniff them. When all was said and done, there was nothing awry. The captain apologised profusely. We got free entertainment, but I would have preferred free beer. It's just me, you know.