The Trail of the Chocolate Thief (The O'Brien Detective Agency #2) by James Heneghan

"Hush," said Sadie, "I hear
something."

Clarice leaped to her feet and
pointed. "The doll!" she screamed.
"It's gone!"

Someone is stealing toys, and the
O'Brien Detective Agency is on
the case! A trail of clues leads 
Clarice, Sadie and Brick all over
the nighbourhood, without
bringing them one step closer to 
the clever thief. They are 
running out of time . . . but
maybe, just maybe, this thief's 
cleverness will give him -- her?
-- away!