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. They try to persuade him to join them but he refuses, convinced now that his family are dead. Quatermass, aided by Gurov, who has travelled to London from Moscow, assembles a team of scientists to find a solution. He deliberately selects old people for the task as they are immune to the effects of the alien force. Quatermass decides to set a trap. He 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. Quatermass does not believe this will be sufficient to destroy the alien machine but he hopes that it will damage it enough to make it go away. 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. Kapp tries to warn them away but is shot by Kickalong. 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".