The Epic of Beowulf is a Viking legend, known to us only after being written down in proto-English some time between the 8th and 11th centuries. The only known copy of the original story was discovered in the late 18th century after just barely surviving a fire in the repository where it was held.
The theme of a malfunctioning holodeck was previously explored on an episode of Star Trek:TNG, The Big Goodbye (1988). In that episode, Captain Picard enters a 1940's "Raymond Chandler-ish" private detective novel bringing Data and Dr. Crusher with him before things go crazy.
The trivia item below may give away important plot points.
Captain Janeway sports a new hairstyle - perhaps as a test, or a passion of a particular stylist - as a similar style shows up later in the series on Ensign Wildman (Elogium S2-e4) and finally landing on Seven of Nine for it's final character.