Arlington County library officials are asking for the public’s help in solving a mystery. They just can’t give you many clues about the mystery.

What they will say is that something of value was found with a donation made last week during the Arlington Friends of Library book sale, and they really want to get it back to its rightful owner.

But they can’t tell you what the something is. They won’t say where the something was found. And don’t ask which library the something turned up in.

“It could have been dropped off at any library location, although volunteers found it during processing at the Central Library,” library spokesman Peter Golkin said.

Golkin said the item was tucked inside something.

A book? A videotape? Officials won’t talk about that either.

Golkin did say there were no distinguishing marks on the item, which was less than 30 years old.

“It could have belonged to someone who passed away and family or friends or a landlord were cleaning out their effects,” Golkin said, theorizing on how the item ended up in the hands of the library. “The true owner may not even be around anymore.”

But library officials believe that it is valuable enough that they should return it to its rightful owner.

If the item isn’t claimed, “we’ll consider it a donation,” Golkin said, but that won’t happen for several weeks. “We’re in no rush to close the case.”

If it’s yours, and you’d like it back, call Central Library Manager Margaret Brown at 703-228-5952. Be prepared to answer detailed questions about it. Whatever it is.