Five years into a multi-decade deep space mission, a team of eight scientists—four women, four men—explore a dwarf planet near the Kuiper Belt, loading soil samples, rocks and artifacts onto their spaceship, Gretel. Inadvertently, they bring aboard a stowaway, an unseen entity which has grown exponentially in a very short time, and is trying desperately to escape from Cargo Hold 4.
The ungodly howling, hammering and screeching coming from the hold on Gretel becomes unbearable, affecting the crew's sleep and work cycles, and threatens the integrity of the ship itself. Captain Desna knows they must take action to survive, but is unsure how to get the alien life form off the ship. To learn more about the disruptive organism, she decides to execute a dangerous spacewalk. However, she is the only one small enough to enter the exterior purge vent leading into Cargo Hold 4.
Battling her cumbersome spacesuit within the claustrophobic vent tube, and running low on oxygen, Desna finally manages to edge herself close enough to the small intake opening to glimpse their unwelcome visitor ... and can't get her mind to accept what her eyes are seeing.
