Mantis review — A return to the killer’s world that struggles to hold its own

Mantis arrives as the long-awaited spin-off of Kill Boksoon, carrying the weight of a breakout original that mixed motherhood, moral ambiguity and merciless action. Expectations were high: another sharp plunge into the secretive assassin industry, this time centered on Han-ul, the man known as Mantis. Yet what unfolds is a movie that delivers clean choreography and a clever ending but falters in emotional gravity and narrative drive.

The promise of Mantis was tied to the boldness of Kill Boksoon. That first film stunned with its mix of intimate vulnerability and ruthless efficiency. Audiences (myself included) expected the same confidence here, but this time the story feels less daring. It expands the assassin universe without the same conviction, leaning on familiarity rather than carving a new, visceral identity.

Sequels in action franchises can hold or even raise the bar and John Wick proved that with a second chapter as electric as the first, but Mantis cannot match its own starting point.

The weight on Mantis himself

Han-ul (Im Si-wan) returns to the MK assassin network after time away and finds a hierarchy fractured, rules rewritten and alliances shifting. At his side stands Jae-yi (Park Gyu-young), a rival turned ally who embodies both danger and trust. (You’ll surely remember the duo from Squid Game if you haven’t been living under a rock and missed the globally acclaimed Korean series.)

In the shadows waits Dok-go (Jo Woo-jin), an old legend determined to reclaim influence. The stage is set for a power struggle that should feel tense and unpredictable, yet too often it plays out as routine exposition. The film says more than it shows, leaving key dynamics cold.

Moments that should plunge us into the unstable politics of this world come off flat. The meetings and backroom deals that define the new order lack suspense or menace. There is little sense that Han-ul’s return truly destabilizes anything. Instead of feeling the pressure of a man trying to reclaim relevance in a deadly industry, we watch a series of functional conversations that move the story without building tension or depth. The universe that once felt dangerous becomes a map with empty borders.

Performances that carry uneven writing

Park Gyu-young gives the film its strongest pulse. Her portrayal of Jae-yi is sharp and layered (and I expeced no less from her after her work in Squid Game), mixing a survivor’s instinct with flashes of vulnerability that feel earned. She can communicate an entire backstory in a glance, and she holds the screen with commanding authority whenever the plot threatens to unravel. Without her, much of the movie would drift into forgettable territory.

Im Si-wan, unfortunately, never finds the weight required of a character who lends his name to the title. Han-ul reacts more than he acts, a passenger within his own story. The script gives him little interiority, and what is hinted at feels too shallow to sustain a narrative. His presence should anchor every power shift, yet he often disappears into the background as supporting players take control of scenes.

For a film named Mantis, the man at its center is strangely hollow, and this emptiness drains urgency from the whole experience.

Action with polish, emotion with limits

When Mantis leans into physical conflict, it comes alive. The fight scenes are cleanly staged and sometimes brutal enough to remind viewers of what made Kill Boksoon compelling. The choreography is crisp, the camera work stylish without losing clarity, and a few set pieces build genuine momentum. These sequences prove the technical team understands action.

Outside those bursts, however, the story loses strength. Scenes meant to deepen character become static exchanges of information rather than lived emotion. Attempts to explore Han-ul’s psychology barely skim the surface, and the pacing grows heavy.

The underworld that once felt alive with danger and moral compromise now seems like a stage waiting for the next fight scene. Without emotional stakes tying the violence to something larger, the spectacle of combat fades quickly after it ends.

An ending with bite but not enough to save Mantis

The finale tries to reclaim some of the lost spark. The final twist lands with intelligence, humbling a capitalist villain who believes power can be bought and reshaping the balance within this universe. It's satisfying to watch the tables turn and to feel that, at least in its last act, the film remembers how to surprise.

Yet a sharp conclusion cannot undo the drift that came before. Two hours of uneven writing and an uninspired lead weigh heavier than a clever closing move. Mantis needed a protagonist capable of commanding attention and driving change, but Han-ul remains a passive figure. Where John Wick grew bolder and richer in its second outing, this story becomes safer and thinner, losing the audacity that made the original stand out.

Rating with a touch of flair: 2 and a half out of 5 blades — two gleaming and one broken.