Juggernaut

Voyager encounters a damaged and adrift Malon freighter in danger of releasing deadly theta radiation into that sector of space and rescues two crew members. Captain Janeway sends a repair crew to try and contain the radiation spread. Before they embark on the mission, the two crewmen warn them about mythical monsters that are said to wreak havoc aboard ships.

Synopsis adapted from TVmaze (CC BY-SA 4.0)