S1·E30 Town of Terror

The guys arrive in a brick basement on the North Atlantic coast in 1978. It has advanced electrical equipment, and they are attacked by an overalled man. He collapses dead, then gets up and disappears in a cloud of smoke. They go upstairs and are paralyzed by an alien-android disguised as an old woman. The aliens are preparing to steal Earth's oxygen. The Project staff execute a lateral transfer and free the guys. They escape to a seemingly empty town surrounded by a force field and filled with paralyzed townspeople. A young couple, Paul and Joan, find the guys and tell them about the oxygen-stealing plot. Meanwhile the alien androids infiltrate the Project base, seal it off, and start sucking out the oxygen through the Tunnel itself. The guys must destroy the operation at their end. They fight off the androids and use explosives to blow up the alien HQ.