Unfolding in near real time, this riveting thriller starring Helen Mirren puts the ethics of drone warfare under forensic scrutiny.

The film focuses on a diverse group of players at the centre of the action in four different locations, all of whom have their own agendas and scruples as they strive to knock out a terrorist cell.

In Nairobi, Barkhad Abdi’s undercover field agent puts his life on the line spying on the terrorists’ safe house; from his base in Nevada, Aaron Paul’s conscience-stricken US air force officer agonises over his role as he pilots the Reaper drone flying overhead; Mirren’s steely colonel directs the operation from Surrey and remains unflinching when the mission’s parameters change; while, over in Whitehall, Alan Rickman’s sardonic army officer advises a group of politicians as they dither and try to pass the buck.

Screenwriter Guy Hibbert and director Gavin Hood rather over-egg the plot – adding a pair of would-be suicide bombers inside the house and a cute little girl selling bread outside – but they ratchet up a great level of suspense while making the characters’ moral dilemmas the most gripping element.