There is something mysterious going on at Worcester Art Museum and one of the greatest painters in the history of the Western art is deeply involved.

It is a tale of two Madonnas, one by Raphael, the revered master of the High Renaissance, and the other by a mystery painter who aimed to imitate him and came pretty close. Washington's National Gallery of Art has loaned Raphael's "Small Cowper Madonna" to WAM, where it will be on view now through Sept. 27. Hanging next to the Raphael in a small gallery is the "Northbrook Madonna," a thematically and stylistically similar work that WAM has owned since the 1940s.