Chatou Stowaway should have sneaked onto a better movie.

It’s not that Netflix’s latest is a bad film. But given the stars, given the studio, given the zeitgeist of space travel, you can’t help but hear “Hollywood, we have a problem” echoing in the background of this sluggish thriller.

Which is a shame, given the terrific cast and the streaming service’s hot streak (it led all studios with 36 Oscar nominations and nearly doubled its wins with seven statuettes Sunday). And space travel — to Mars, no less — is enjoying a second heyday thanks to NASA’s latest triumph and SpaceX’s high-profile achievements.

Alas, Stowaway succumbs to melodramatic tropes and a plot twist that requires booster rockets to suspend disbelief.

Toni Collette, Anna Kendrick and Daniel Dae Kim (Lost) star as three astronauts bound for a two-year trek to Mars when they discover an unplanned passenger (Shamier Anderson) aboard who jeopardizes the mission and their lives.

The movie’s premise alone is a heavy payload. The film largely glosses over how a technical engineer would get stuck aboard the rocket (did no one share the launch date with him? Would no one have noticed the engineer did not report back to duty?). And while Stowaway focuses on a queasy moral dilemma — there’s oxygen enough for only three passengers — the film never quite seems quite up to answering it.

Collette plays Marina Barnett, the commanding officer of the mission, backed up by medical officer Zoe Levenson (Kendrick) and biologist Kim (Kim). All share in a terrific opening sequence, in which they try to keep their nerves — and stomachs — in check as their ship rattles and moans into the final frontier. It’s as good as many finales of other space films. If only it could muster as much drama at story’s end.

But Stowaway hits a lull after Marina discovers injured technician Michael (Anderson), who drops unconscious from an overhead compartment like a bleeding Tribble in Star Trek. We learn that Michael lives alone with his sister, whom he saved from a fire that killed his parents, and had no intention of space travel.

Thus begins the emotional ordeal of the astronauts. Kim is pragmatic, and argues there is no room for a literal hanger-on. He even offers Michael a suicide injection as a solution. Levenson is the astronaut with a heart of gold, who refuses to take die for an answer. Barnett is caught in between — and downright weepy over the conundrum.

And it’s those tears that help undermine the movie. Recent space travel movies like Gravity, The Martian and Interstellar found their footing on a similar theme: Resolution in the face of death. That determination is missing here, and Stowaway leaves audiences to ask: What do you do with a fourth occupant of a three-person raft?

There’s a solution, of course, but it will take a risky maneuver to get more oxygen to the crippled ship. Two astronauts must scale a towering tether to pierce an oxygen tank and extract air. But here, too, Stowaway isn’t sure what to do with the drama. The astronauts must face deadly drops thanks to the “artificial gravity” of the spaceship. But vertigo is a lot more palpable in natural gravity, in a real-world setting like a mountain or skyscraper. A starry backdrop isn’t as squeamish as director Joe Penna would have us believe.

There are nice touches throughout Stowaway, including some surprising character fates and a chance to hear Collette’s rarely-used native Australian accent. Anderson is a solid newcomer.

But given all the promising ingredients of the film, viewers may find themselves feeling like they rode steerage in Stowaway.