The spacecraft Odyssey II is set to embark on a mission to retrieve a foreign object that could potentially save humankind, but the plan quickly goes awry when five untrained kids sneak aboard and are unable to stop the launch sequence.

The Odyssey II is a spacecraft prepped for a mission to retrieve a foreign object that can potentially save humankind; the spacecraft prematurely launches with five untrained pre-teens on board.

Tension escalates as Elliott plants seeds of distrust about Will, whom Elliott suspects is collecting mission information for his reporter mother; Samy works with Matilda's inventor to probe the AI's role in the launch.

A small toy clogging the toilet leaves only one working bathroom, so the kids work together to dislodge the toy; on Earth, tempers flare between the parents while Matilda's inventor devises a bold plan to hijack the AI.

Mission Control uploads a virus onto the Odyssey in an attempt to take control; Matilda fights back by shutting everything down, and the true vulnerabilities of the kids come to light.

A small hole in the ship threatening the oxygen supply can only be repaired from the outside. Martin is forced to become the first kid to ever attempt a spacewalk as he is the only one who can fix it.