Stowaway (2021) is a tense, character-driven sci-fi thriller that explores profound ethical dilemmas in the unforgiving vacuum of space. Directed by Joe Penna, the film follows a three-person crew—commander Marina Barnett (Toni Collette), biologist David Kim (Daniel Dae Kim), and medical researcher Zoe Levenson (Anna Kendrick)—on a two-year mission to Mars. Their journey takes a catastrophic turn when they discover an unintended stowaway, launch support engineer Michael Adams (Shamier Anderson), whose presence damages the ship's life support systems, leaving insufficient oxygen for all four to survive.

The film excels in building claustrophobic tension and moral complexity, as the crew grapples with an impossible choice: sacrifice one to save the others, or risk everyone perishing. Performances are standout, particularly Anna Kendrick's empathetic turn and Toni Collette's authoritative yet conflicted leadership. The direction emphasizes realism and suspense over action, using the confined setting to amplify emotional stakes.

While some critics noted pacing issues, Stowaway succeeds as a thought-provoking adventure that questions human values under extreme duress. Its 5.7 IMDb rating undersells its engaging plot and strong performances. Viewers should watch it for a gripping, intimate thriller that prioritizes ethical drama over spectacle, making it a compelling watch for fans of hard sci-fi and moral narratives.