A tense and harrowing incident unfolds at a local grocery store just as it is about to close. Suddenly, six masked, armed individuals storm inside, taking everyone present hostage and immediately opening fire on one of the employees, creating chaos and terror. Among the intruders is a man known as Spooky, who is instructed to locate someone among the hostages. When he identifies a woman as "one of them," she attempts to flee but is quickly shot down in cold blood, highlighting the brutal determination of the attackers.
Meanwhile, a police officer who was inside the store manages to fight back, successfully shooting one of the masked men before calling for backup. He also manages to kill Spooky before he can finish his grim task. Sadly, the officer himself is soon killed, leaving the situation escalating out of control. As police arrive on the scene, the group of kidnappers debates whether to continue their operation or abandon it. The group's leader, a man named Ritter, assures them that they need to complete their mission. They release the hostages already checked by Spooky and move the rest to the back of the store for further inspections.
As the group investigates one of the dead bodies, they realize it was infected with a parasitic organism that breeds inside humans, adding a horrifying biological threat to the already tense situation. With Spooky dead, they resort to a brutal method to identify who might be infected: cutting off a finger from each hostage for Sterling, the group's doctor, to test. This gruesome process underscores the group's desperate efforts to prevent the spread of infection.
Outside the store, police officer Seth, whose stepdaughter Whitney works at the store as a cashier, takes command of the police operation. They uncover that Ritter was once a rocket scientist and learn about the group's terrifying purpose: hunting and eliminating people infected with an alien parasite that arrived on Earth inside a meteorite. The police are skeptical but are forced to consider the unsettling possibility of extraterrestrial biological threats.
Negotiations ensue, with the police agreeing to help Ritter by bringing a woman named Charlotte, a former group member with mysterious abilities similar to Spooky's. In a chilling turn, the attackers inside discover another infected individual and kill her, indicating the parasite's deadly spread. The situation quickly turns deadly when the revived body of the police officer attacks, killing several more hostages and captors.
Ritter then reveals that the parasites are structured into two groups: several females and a single king, essential for the parasites’ survival. Without the king, extinction would be inevitable. The kidnappers believed one of the people in the store was host to the king, which is why they targeted the entire place.
Meanwhile, Seth and Charlotte infiltrate the store. Using Charlotte's special abilities, they lure the infected officer into a trap. Seth leads Whitney and Benny, a store clerk who volunteers to have his finger cut off to spare Whitney further trauma, to safety outside. Ritter successfully removes the parasite from the infected cop, but is shot and killed by police who want to eliminate the threat.
As Sterling is taken into custody by Seth, Charlotte realizes that the parasite Ritter removed was not the king. In a tense moment, Benny overhears Seth communicating with other officers, claiming Benny himself must be the king. Benny then deduces that Whitney might actually be the true host of the alien king, as she remains untested and is the only one left alive who could harbor the creature. In a chilling climax, Benny aims his gun at her, but her eyes and veins darken dramatically, and the scene fades to black amid her screams, hinting at an even greater threat still lurking within.
This story is a gripping exploration of paranoia, biological horror, and survival, emphasizing how fear and desperation can drive people to extreme measures when faced with an existential extraterrestrial menace.
