I don't think I've ever made a recommendation like this: every adult American should see this movie. In a democracy, we are ultimately responsible for sending young men to foreign countries to engage in deadly, dangerous activities; we should know something about who they are and what they do. You won't easily find a better learning experience than this movie. The IMDB parental guide uses the phrase "hard to watch" four times; that's exactly why you should.
The title (and the movie's opening scenes) tell you everything about how this movie ends: Marcus Luttrell, played by Mark Wahlberg, is the only one in his Navy SEAL unit who returns alive from a 2005 mission in Afghanistan.
The SEALs are a close-knit team, and we're shown how that happens: training that's close to torture, new-guy hazing, physical competition, zero privacy. Nobody's a loner, everyone gets advice on stuff like what color to paint the kitchen back home, or whether a prospective groom can afford to buy his fiancée a fancy horse as a wedding present.
Marcus and three comrades are picked to locate/capture/kill a particularly dangerous Taliban commander, Ahmad Shah. They're dropped in at nighttime from a helicopter, and they make their way to an outlook above the village where Shah is suspected to be. Through sheer bad luck they are discovered by some civilian goat-herders. Rules of combat say: let 'em go, and they do. Communications are flaky enough to prevent a quick exit from the area, and the team is quickly located by a lot of Taliban.
What follows is horrible.
Director/writer Peter Berg made this movie after reading Luttrell's memoirs; although he clearly means to honor the servicemen and their sacrifices, he scrupulously avoids politics, letting the situation and the events speak for themselves.