After a cosmic event damages Covenant's solar sails, the crew's sleeper pods are activated — though during awakening, the ship's captain, Branson (James Franco), is killed in a pod malfunction. The second-in-command, Chris Oram (Billy Crudup), reluctantly takes the helm, with the ship's terraforming expert Daniels (Katherine Waterston) as his deputy. On a crew mostly consisting of married couples, Daniels is also Branson's wife.
The ship picks up a signal — to the tune of John Denver's "Take Me Home, Country Roads" — from a distant planet. Seeing the planet could sustain human life and is a lot closer than the planet they were originally going to colonize, the crew decides to investigate.
Once on the new planet, they make two dangerous discoveries. One is a form of the familiar chest-bursting alien creatures. The other is the long-stranded David, who confides in his lookalike Walter about the planet's true menace.
Scott, working off a script by John Logan ("Spectre," "Skyfall") and first-timer Dante Harper (with story credit going to Jack Paglen and Michael Green), nimbly switches from nail-biting tension to pulse-pounding action scenes. He also homes in on the characters, a motley assembly of space travelers ranging from Crudup's devoutly Christian commander to the foul-mouthed pilot Tennessee (Danny McBride), who scramble to survive the alien threat.
Waterston (last seen in "Fantastic Beasts and Where to Find Them") takes on the Sigourney Weaver mantle well, showing the same resolve and vulnerability Weaver's Ripley did back in '79. The star player, though, is Fassbender, whose dual roles encapsulate one of science fiction's most lasting debates: the loyalty of robots who know they are superior to the flawed humans they serve.
So much works well in "Alien: Covenant" that it's a shame that the finale is a fizzle, a standard display of special-effects fireworks delaying a plot twist any observant human can see coming from a parsec away. The disappointing ending turns what could have been a great "Alien" installment into merely a good one.