(STMW) — Workers at Valparaiso branch of the Porter County Public Library in Indiana got a surprise when they realized a donated book had been hollowed out — and had a gun hidden inside.

The donated book was Robert Stone’s novel “Outerbridge Reach.” But it was really just a holding place for a gold A.S.M. .31-caliber, a single-shot black powder handgun with a wooden handle.

Because the library doesn’t record donors’ names, police don’t know whose gun it is.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2012. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)