For months, Auckland City Library staff had been trying to figure out why books were disappearing and then reappearing under the shelves and hidden in different places all over the building.
It turns out they are being read by the city's homeless, people who cannot have a library card because they don't have a home address. They admitted to stash the books away with a bookmark so they could make sure they'd find them again and could continue reading them the next day.
"A lot of our street community were wanting to put them underneath the couches or under book shelves and kind of hiding them in places," librarian Sean Taylor told TVNZ.
"And for a librarian it's really weird, we're like 'oh what's this book doing here?' and we've put it back."
The library thought maybe bored kids were playing games on them.
The mystery of the missing books was only solved when the library called a meeting with the city's homeless.
Some rough sleepers do have a library card as the library allows them to use the City Mission as their home address but others admitted they were worried about damaging the books if they took them out of the building.
"That community really values the services we offer and treat the books with a great deal of respect," Auckland Libraries manager Rachael Rivera told the Guardian.
"A lot of the guys that come in are extremely well-read and have some quite eccentric and high-brow literary tastes ... people are homeless for so many different reasons, and being intelligent and interested in literature doesn't preclude that."
According to Rivera, around 50 homeless people visit the library daily.
A new bookshelf for the homeless has now been created in the library, as a place to safely store the books behind the main counter so the readers can easily find them.