Britain is in the grip of a deadly flu virus, which is now spreading throughout the world. When people start dying in their millions, a handful of survivors are left struggling to stay alive as society crumbles around them.

Abby Grant is a housewife and mother who begins the desperate search for her son. On her journey she meets a variety of people whom fate has spared.

The new world could be a dangerous place, and their only hope is to stick together.

Abby and her new friends discover that supplies won't be shared equally in the new world. A gang of armed thugs have laid claim to all the shops in the area leaving them short of food and water.

Greg receives an attractive offer which could give him a comfortable life, but taking it would mean turning his back on the others.

When visionary spiritual leader John turns up mysteriously at the survivors' door with his ragged group of passionate disciples, some in the house are suspicious of his motives, in the penultimate episode of Adrian Hodges' post-apocalyptic drama series.

Charming and eloquent, John is a preacher with a unique perspective on the new world, but the family's opinion of him is split. Is he as innocent as he seems, or does he have more sinister motives? A woman in John's group is pregnant, and Abby allows her to stay until the baby is born. Anya fears that she will be forced to reveal that she is a doctor if there are any problems with the birth. Worse than that, she picks up on some unusual remarks by John which make her concerned for the group's safety.

In the final episode of the series Abby and her friends find themselves on the run from Samantha, who has formed a dangerous alliance that threatens everyone's freedom. Meanwhile, Sarah is confronted by a face from the past, which leads her to betray her new friends.

When Naj goes missing, the family face the danger of the city in order to find him. Naj is befriended by a feral boy named Darren. Darren lives with the sinister Craig and June, who look after a group of children who forage amidst the ruins of the city in return for the shelter and protection.

With his adopted family searching for him in the deserted city, time is rapidly running out, and Dexter is only a step behind them all...

Greg has been wounded by a gunshot, Anya, Al and Tom frantically search a nearby hospital to find vital medical supplies. With the building on fire, it suddenly collapses, leaving Anya and All trapped. Whilst Greg is now perilously close to death.

Abby still remains kidnapped at the Lab as the Scientists seek to find a vaccine using her immune system.

The post-apocalyptic drama reaches its thrilling conclusion as the fates of the Family, the Lab and the rest of the world come crashing together in a deadly showdown.