“Death’s Other Dominion” is episode five of season one of Space: 1999.
In some tunnels in the ice, two men who look human see that Earth’s Moon is approaching their world. And they recognise it as Earth’s Moon and one, Dr Cabot Rowland, wonders if Alpha is there. The other, Jack, says that mortals should have no contact with those of the eternal breed. Rowland hails Alpha and Commander Koenig hears him talking about how this is Ultima Thule, a lost paradise. They have long life and the Alphans can share. The smog is closing in and they will lose contact. In the background, Jack is shouting to stay away.
Eagle 1 approaches Ultima Thule; the commander contacts Paul and asks if there’s been any response to hails. No, and the computer says the weather is terrible. Koenig says they may drop out of contact as well. They enter the smog; Victor and Dr Russell are in the back. She says the temperature at the origin point of the broadcast is -60. The computer takes over for an emergency landing; once the Eagle is down, all four head out in protective gear.
Jack is howling when Rowland finds him; in a combination of rational and not, he says the Alphans are coming. Rowland attempts to contact them. The Alphans are in a howling blizzard; Victor says they’ve arrived at the origin of the signal. They briefly get a hail, but the commander suggests they head back to the Eagle and let the Thulians find them. On the way back, they get separated and it looks like the beacons aren’t working. A search party finds them.
Victor, Koenig and Russell are brought into the Thulians’ ice caves, which are a mix of high and low tech. Koenig comes around and realises Alan isn’t with them; Rowland dispatches a search party; it will soon be -170 outside. The Thulians have adapted to the conditions. Jack, who is more than a little erratic, thinks that death on Thule would be a marvellous thing. Outside, Alan collapses in the snow.
Dr Russell wakes and Koenig tells her the people are the survivors of the Uranus Expedition of 1986. He introduces Rowland. Rowland introduces Jack, Jack Tanner, the mission’s commander.
Outside, Alan gets up. He collapsed near Eagle 1 and makes his way inside.
Rowland tells the others to only eat their rations. When the Thulians arrived, the food made them violently sick. They adapted in time, fortunately. The drink is fine. The last report of the expedition was from Tanner saying the probe was breaking up. Rowland says they travelled beyond the furthest limit of the known universe, and then beyond. They crash-landed here. The search party returns; they didn’t find Alan. Rowland says they will continue tomorrow; now, they should sleep.
Main Mission is trying to contact them again. Rowland hears and goes to short out part of their communications array. Not a great sign. Alan also hears as he comes around, but Main Mission can’t hear him. Sandra suggests that the Eagle might not have enough power. Alan takes a look at Eagle 1’s exterior; he has to take off before the craft is buried in the snow.
Rowland is lying about trying to contact Alpha. It also seems that the Thulians have been there a lot longer than thought. They have lived a very long time, and Rowland wants to find the secret. The prospect of conquering death is an attractive one.