In the aftermath of a near-fatal car accident, four people returning from a funeral realize nothing will ever be the same when they look to the sky and see a mysterious alien ship hovering over their home city.
The group returns home and, amid newscasts warning them to stay put, struggle to decide what they should do next. As they attempt to track down a missing family member, a horrible realization about her whereabouts comes to light.
Steven heads into the city alone to try and track down his missing step-sister, but matters are complicated when it appears the people she is with may not be willing to let her go without a fight.
Dan, Chloe and Nicole head to the local supermarket to try and get supplies, only to find it has been overrun with looters. The group must fight for their survival when a confrontation inside turns violent.
Steven and Katie reach the local church in their efforts to find Sarah. As the priest inside encourages them to stay with the rest of his congregation, Steven battles with how best to protect his family.
Nicole finds herself in the company of a mysterious stranger and must decide who she can trust when he asks for her help in an unusual matter.
Dan and Chloe take shelter in her parents' home. As they try to cope in the aftermath of events at the supermarket, things turn deadly and it is clear they're not out of danger just yet.
Nicole and Sanders have to work together when their mysterious new visitors turn against them, and they are forced on the run.
We meet the group before things all began and see how they came together but did they receive forewarning of the impending attack?
Still separated, the group all make a last-ditch attempt to reach the farmhouse, but are they truly safe?
A week after the alien ships arrival over Bristol, the group struggle with what to do next. Steven still hasn't made it to the farmhouse, and something is calling Dan back toward the city.
The fate of Steven and Katie is revealed, and we meet the mysterious Isaac. A broken man for whom the arrival of the ship changed everything.
The group return to the farm, only to find they have been visited by a mysterious stranger who comes bearing a warning of things to come.
The government interrogate a prisoner who may have information about the UFO. However, matters are complicated when potentially hostile forces arrive to take over.
A flashback to Bristol of the past reveals how a chance discovery almost 200 years prior may have led to the arrival of the UFO in present day.
The group are forced to break into a historic Bristol building in order to prevent the impending attack. However, it may still be under guard and government forces are in pursuit.
Nicole is forced to put her brief training into action when a stranger arrives at the farmhouse. Meanwhile, Brennan and Cole plan retaliation against a covert government team.
Nicole fights for her life as the government attempt to track down the rest of her group. She receives help from an unlikely ally.
In a last ditch attempt to prevent the invasion, the group venture into the tunnels beneath the city. However, they may not be the only ones down there.
The group have a tough decision to make when it becomes clear the only way to prevent disaster is to make a significant sacrifice, and the clock is ticking.