(Jack cradles Ianto as they both succumb to a deadly virus released by the 456)
Jack: It's all my fault.
Ianto: No, it's not.
Jack:Don't speak. Save your breath.
Ianto: (tearfully) I love you.
Jack: Don't. Ianto?
(Ianto starts slipping away)
Jack: Ianto. Ianto, stay with me. Ianto, stay with me, please. Stay with me.
(Ianto, though weakly so, briefly regains consciousness)
Jack: Stay with me, please.
Ianto: Hey. It was good, yeah?
Jack: (breaking down) Yeah.
Ianto: (crying) Don't forget me.
Jack: Never could.
Ianto: A thousand years' time... you won't remember me.
Jack: Yes, I will. I promise. I will.
(Ianto's eyes close for the last time)
Jack: Ianto... Ianto? ...Don't go. (crying) Don't leave me, please. Please don't.
The 456: You will die, and tomorrow your people will deliver the children.
(Jack kisses Ianto one last time, and keels over dead from the same virus that killed Ianto)In 1965, Jack was picked to hand over a busload of children to the 456. He thought he was chosen because of his immortality, but actually, it was because people figured that he wouldn't care. He did care, of course, and vividly remembers trading in twelve children in the 456's "protection racket". If he hadn't done it, the Earth would have been devastated by a plague, engineered by the aliens. Jack had already lived through the Spanish Flu — he couldn't bear to see the Earth suffer like that again.When Jack walks back into the Hub, Clement — the boy that got away — recognises him from every single nightmare he's ever had since that night. He promptly shoots Jack dead and breaks down crying. Gwen manages to calm him down.The governments of Earth, and UNIT, now have to decide what to do. Frobisher tries to bargain with the 456, but the counter-offer of a few dozen failed asylum seekers from refugee camps is deemed unacceptable by the aliens. The children are now all chanting the exact number of sacrifices that each nation needs to make. Prime Minister Brian Green makes the decision to exempt everyone present at the meeting from having to give up their children. Home Secretary Denise Riley MP finally suggests giving up children from lesser schools, knowing full well that it's the most horrible decision of her life. Lois is still meekly recording it all.The 456 allow one cameraman in a protective suit into the container. Three distinct life forms are detected inside... one of which is an emaciated, hairless child, hooked up to the 456 through a mouth mask. It's one of the children from 1965, now ageless and tethered to the 456 forever. This is what would happen to every child given to the aliens.Frobisher and Jack talk on the phone, and Jack learns that his daughter and grandson have been kidnapped. He threatens to kidnap Frobisher's own wife and children in return, but Frobisher knows that Jack never would.Ianto's sister and her husband have set up a makeshift daycare for the neighbourhood's children. They charge money, because times are just that tough. Ianto calls them and lets them know bits and pieces of what's going on.Prime Minister Green tells Frobisher that the government will not be blamed. The children will be said to be taken for vaccinations to prevent more chanting. The government, people will think, was simply tricked. Frobisher still hasn't slept, hasn't eaten, hasn't been allowed to explain things to his family, and has found himself helplessly agreeing with everything on his path. But he knows that as long as he agrees, his own children will be safe.The Torchwood team determines that Lois' footage gives them leverage to blackmail the cabinet, and force their way into Thames House. Lois finally speaks up, meekly at first, then with more conviction. She reveals that she works for Torchwood, and that everything said in the room has been recorded. Meanwhile, Rhys runs off with the laptop, ready to press "send" on the blackmail if the government should decide to go through with the sacrifice of millions of children. Agent Johnson finds Gwen, but Gwen shows her what's going on, and Johnson promptly does a complete Heel-Face Turn.Ianto and Jack try to destroy the 456, but the aliens release a gas attack and a high-pitched radio signal that kills Clement. Everyone in Thames House is affected by the gas, and all the doors are locked. Dekker escapes death by putting on the protective suit. Ianto, however, is dying. He says a tearful goodbye and an "I love you" to Jack, who can't say the same thing. Jack kisses Ianto's dead body on the lips, then dies beside him.Jack resurrects as Gwen enters the Thames House after the virus has been purged. Soldiers have lain out the casualties for identification. What happens next is the most tear-inducing moment of the series. Gwen and Jack gaze upon their fallen friend Ianto who is now wracked with pallor, and obviously not coming back to life like Jack. Both Gwen and Jack cry uncontrollably in extreme grief, having lost another Torchwood member. Gwen tearfully, says, "There's nothing we can do." The two surviving Torchwood operatives are emotionally shattered.So were the viewers. Almost no one took Ianto's death well. The really devout fans of the Jack-Ianto pairing created a shrine in honor of Ianto Jones in Cardiff Bay where the Torchwood Three entrance would be in real life. Cue hundreds upon hundreds of desperate pleas to bring back Ianto of all sorts. And believe it or not, it still stands today as a popular attraction in Wales, sometimes getting revamped as fans add on to it or modify it after stormy weather messes it up.
— Ianto Jones says his Famous Last Words to his lover Jack Harkness