Star Trek: Voyager - 10 Most Anxiety-Inducing Episodes
7. Heroes and Demons
While enjoying time off on the holodeck playing his Beowulf holonovel, Harry goes missing. When Chakotay and Tuvok go in after him they too disappear. Not wanting to lose any more crew members, Janeway sends in the Doctor to investigate, as he is the only crewmember who would not be affected by the photonic energy causing the disappearances.
During his first attempt the Doctor comes into contact with the photonic energy and when he is transferred back to sickbay, his arm, which contacted the energy, is missing. This is where we realise the Doctor may not be able to save the missing crewmembers. It's the Doctor's first away mission and it nearly becomes his last!
Not one to give up, the Doctor goes back into the holodeck after the crew determines that the photonic energy wants the samples taken from a protostar that were beamed aboard just before the problems started. He gives the energy what it wants and Chakotay, Harry and Tuvok are safely returned, but not before we nearly destabilise from the anxiety we produced watching the episode.