Answer:

WHERESWALDO

AnswerCrossword Clue
WHERESWALDO1987 kid's best-seller
WHERESWALDOPepper missing? (Handford)
WHERESWALDOKid's book with a hidden character
WHERESWALDOQuestion posed by a 1987 children's best seller
WHERESWALDOPopular children's book series ... whose protagonist is "hiding" in the circled letters
WHERESWALDOMissing person alert?
WHERESWALDOQuestion from Martin Handford
WHERESWALDOMissing person alert
WHERESWALDOPopular seek-and-find series
WHERESWALDOQuestion that signals a missing person alert
WHERESWALDOQuestion in some kids' books
WHERESWALDO1987 children's best seller