Jack Bruno (DWAYNE JOHNSON) is an ex-con who now works as a cabbie in Vegas. After handling some goons that work for a crime boss who has a connection to him, Jack is surprised to find teens Sara (ANNASOPHIA ROBB) and Seth (ALEXANDER LUDWIG) in his backseat with a wad of cash and a desire to be driven into the desert. He's reluctant, but the money looks good, so he proceeds, only to then be pursued by Department of Defense official Henry Burke (CIARÁN HINDS), and his subordinates Matheson (TOM EVERETT SCOTT) and Pope (CHRIS MARQUETTE), among other feds, who want the kids.
And that's not because they're juvenile delinquents are runaways, but rather extraterrestrials who've crash-landed on Earth. That's a surprise to Jack who initially thinks their pursuers work for the crime boss, but once the kids demonstrate their paranormal powers, he's a believer. Despite his instincts telling him otherwise, Jack decides to protect the kids, and eventually enlists the aid of Dr. Alex Friedman (CARLA GUGINO), a failed astrophysicist who's speaking at a UFO convention, as well as UFO author Dr. Donald Harlan (GARRY MARSHALL).
As they try to get the kids back to their ship before it's too late, they must not only contend with Burke and his armed feds who are always one step behind them, but also with the alien assassin Siphon (TOM WOODRUFF, JR.) who wants to kill the kids before they complete their mission on Earth.