The library contains a large collection of evidence that Dewey and his "comrade", most likely Kit Snicket, have collected over the years that can send all villains to jail. Simply put, it contains information about every person, place, thing, and event that has had an association with V.F.D. According to Dewey, all the information is archived in underwater rooms organised like "a mirror image of the hotel itself." Judging by that fact, the library is most likely the best chance for prosecuting the fire-starting side of V.F.D.
Although the hotel is destroyed, Lemony mentions that the underwater library has remained safe all these years.
In the TV series, Dewey claims that his library has every information gathered by every V.F.D. agent, scholar, researcher, inventor, scientist, explorer, cartographer, poet, journalist, naturalist, herpetologist, optometrist, receptionist, chef, waiter, taxi driver, sea captain, film director, ballerina, children's book author, and mountaineer. He mentioned this to the Baudelaire orphans when they were walking through the V.F.D. tunnel.
- 27 cakes that Count Olaf has stolen.
- It is also known to have an entry on an interpretation of sausages that went horribly wrong, having destroyed a bathyscape (all of which was a huge accident on Lemony Snicket's part when he mistook the sausages to say K instead of R).
- An interpretation of the law, also described in The Penultimate Peril, that went horribly wrong, but it was the same one that occurred in the book.