The episode opens in Scotland in 1965, with a group of children on a bus at night going through the countryside. The bus stops in the middle of nowhere and they get out and walk into a mysterious light, while one child hangs back.

We then go to the present and Cardiff and see numerous children have stopped moving. It quickly becomes apparent that it is not an isolated phenomena and is widespread, then all the children start moving again. We then follow Gwen into Torchwood Cardiff which is empty and she starts researching the incident.

Jack and Ianto have gone to a hospital, and are checking a recently deceased body and extract an alien “hitchhiker” from it. A Doctor (Rupesh) sees them and chases after them and tells them that bodies are going missing. They both dismiss him claiming their being too much Red tape in the NHS, and drive off.

We then cut to a meeting between an UNIT officer and John Frobisher a senior Home Office civil servant where the children incident is mentioned, and it is made clear the incident was worldwide, and only they and Torchwood could work out what was going on.

Back at Torchwood, Rupesh appears outside and Gwen goes to talk to him when it turns out Jack is thinking of recruiting him. While they are talking Gwen notices that a child has stopped. This time however they start to scream. They then stop and start saying We repeatedly, until they eventually say “We are coming”.

We then see an adult at a care home saying the same thing. The children repeat saying “We are coming” until they revert to normal with no memory of what has happened. The adult however says “they found me”.

Back at the home office, a Mr Decker tells John Frobisher that he warned him about the 456. Frobisher then leaves with Decker and go to a part of Thames House where they discuss a transmission on the 456 and that it was open.
At Torchwood, we find out that all the children worldwide are speaking English. They then discover footage of the man “Timothy White” a patient in a Psychiatric ward and Gwen goes off to see him. Gwens husband Rhys mentions on the phone that the timing of the incidents seems linked to when most children are out in the UK in Britain.

In a meeting Frobisher has with the Prime Minister, it becomes clear that the aliens are known to the UK, and at some point there was an incident with them which they could use the new incident to cover up, if the 456 keep quiet. John Frobisher then mentions having to issue a blank page, which later turns out to be an assassination order. The PM insists on having plausible deniability about and leaves it for Frobisher to handle.

Back in Cardiff, Jack and Ianto both try to find a child, with Jack going to see his grandson, and Ianto his neice, but both fail. Jack then phones Rupesh to see if it has a childrens ward, while Ianto has his car stolen after confessing his relationship with Jack to his sister.

Gwen has a chat with the Timothy, who turns out to be one of the children from the start of the episode whose real name is Clement MacDonald and was from Holly Tree in Scotland. Clement appears to have unnatural “sniffing” powers which he uses to tell that Gwen is telling the truth and tells Gwen that she is 3 weeks pregnant but before she can find more a nurse enters having noticed that a camera was inactive (done by Gwen).

As Gwen leaves, she calls Ianto to search for information on Clement McDonald. This then raises Red Flags, at a British Military (or UNIT) Installation. They discover he is still alive and go to take him in, but he runs away.

At the home office, Frobisher gives a blank page order to his assistant Bridget Spears for people in the 456 folder. A new member of the home office Lois Habiba uses Bridget Spears password (given earlier to set up an automated phone reply) to check what is going on and discovers that an order has been given to kill several people including Captain Jack Harkness.

We then see Jack at the hospital and as he goes to look at a suspicious death Rupesh pointes out, Rupesh shoots Jack from behind. It turns out that Rupesh was on a mission to infiltrate Torchwood but his orders were changed presumably due to the blank page order. Associates of Rupesh then arrive, and operate on Jack. In order so Jack wont suspect anything, his boss a woman called Johnson kills Rupesh and puts him next to Jack before leaving.

Back at Torchwood, Gwen confirms that she is pregnant with a bioscan in the lab, ignoring Ianto who is trying to fill her in on what he has found out. As Jack enters he sees the scan he goes to congratulate her, he accidently puts his hand on the scanner which picks up a bomb in his stomach which is set to go off in 2 minutes. Gwen and Ianto reluctantly evacuate while Torchwood locks down and the bomb explodes still within Jacks chest. At the same time the children start chanting, with the message at the end changing to “We are coming..Back”