Alan Rickman in Eye in the Sky

Exactly what a thriller should be, Eye in the Sky has high stakes, conflicting motives, believable characters with a tangle of personalities, and a ticking clock. If you’ve seen the trailer for this film, you know that British and American military forces have put an “eye in the sky”—an armed drone with a powerful camera—to track members of a terrorist cell in Kenya, including an American citizen and two Brits. It finds them. The rest of the film is “what next?”

When the terrorists are found to be preparing for more suicide bombings, what was intended to be a capture mission soon must be reevaluated—legally, militarily, and politically.

Director Gavin Hood assembled a terrific cast, with Helen Mirren as the U.K.’s colonel in charge of the operation from an underground military bunker and Aaron Paul as the Nevada-based “pilot” of the drone. Alan Rickman (so glad to see him, so unutterably sad he’s gone) is a British lieutenant general supervising the mission from a wood-paneled conference room, along with high-ranking British government officials (reminiscent of the crowded situation room when Osama bin Laden was killed). It’s a room filled with more indecision than people.

On the ground in Kenya is a British agent played by Academy Award nominee Barkhad Abdi, whose life if caught isn’t worth the proverbial plugged nickel, the terrorists in a supposed safe house, the local Sharia law enforcement and security squads, and a neighboring family of innocents.

Most of the movie concerns the deliberations of the groups in the bunker, in the conference room, and in the Nevada “pilot house” as they see what the cameras can tell them—a lot, really—about what is unfolding inside the safe house. They’re aided by a facial recognition expert based in Hawai`i watching the same screens, attempting to verify the terrorists’ identities. Because of the incredible detail of these images, the transitions from screens to street scenes (mostly from the point of view of Abdi) feel seamless.

The key issues are “collateral damage”— inevitable or unacceptable?—and whether a nation can pursue its citizens across friendly countries’ borders. Says Wired reviewer K. M. McFarland, “it’s the best movie yet to tackle the legal and moral quagmire surrounding modern technological warfare.” That review also describes the degree of realism behind the movie’s rather amazing drone technology.

In the screenplay written by Guy Hibbert, the military and the political leaders views’ on the situation differ irreconcilably. The U.K. military want to move; the politicians are cautious. Those views are flipped for the Americans. (Actor Laila Robins, seen locally on stage numerous times, plays a U.S. security official.)

Filmed in South Africa in 2014, the staging of the safe house neighborhood carries a dusty realism that’s a stark contrast to the diplomatic h.q. and the high-tech pilots’ domain. Yet, the decision makers in those far-removed settings are not at all disengaged from the consequences on the ground. Alan Rickman’s final words to a recalcitrant politician are: “Never tell a soldier he does not know the cost of war.”

Rotten Tomatoes critics rating: 93%; audiences 88%.