An Endangered Species - S1.E4

Quatermass emerges from the car park to find the stadium empty. So many have now been harvested that the particles of dust in the air have turned the sky green. Kapp attempts to repair his equipment in order to contact the alien presence, but the Planet People destroy his efforts. Quatermass plans to fake the presence of a large gathering of Planet People at Kapp's observatory and, when the force comes, to detonate a nuclear weapon. Kapp volunteers to stay behind with Quatermass to help detonate the bomb. The pair set up the trap and wait. Suddenly, Kickalong appears with a group of Planet People, including Quatermass' granddaughter, Hettie. The light appears, indicating that the alien force has arrived, but the shock of seeing his granddaughter among the Planet People causes Quatermass to suffer a heart attack. However, aided by Hettie, he is able to detonate the bomb. Later, according to Gurov, "The message was taken. It has not come again. We pray it will never come again".