Workers at a Maine Goodwill store got quite a shock when they opened a donated book: They found a gun inside.

An employee at the Ellsworth store was going through a pile of books received from a central warehouse last week and noticed that one didn't quite feel right. The book was actually a small safe and inside was a .31-caliber black powder pistol.

Employees called police.

There was no identifying information with the book — "Den of Lions" by former Associated Press reporter Terry Anderson chronicling his seven years as a hostage in Lebanon. Police ran the gun's serial number through a national database but did not get a match.

Detective Dorothy Small says the department is turning to social media to try and find the gun's owner.