The last remaining residents of a run-down London tower block find themselves targeted by a deadly sniper, in this tense British thriller written by James Moran. When they witness the brutal murder of a youth in their block, Becky (Sheridan Smith) and the other remaining residents on the 12th floor keep quiet, fearing retribution. One year later, and with the police investigation stalled, they awake one morning to find all communications to the outside world cut. Panic quickly spreads through the group when they begin to be picked off by an unknown sniper with a high-tech rifle, who prevents anyone from escaping the building, and shoots anything that moves. As the situation becomes ever more desperate, the group join together to try and find a way out. But with booby traps at every exit, it soon becomes apparent that not everyone will make it out alive.