Henry, Jessie, Violet, and Benny are getting strange notes from a mystery messenger! An art gallery in Greenfield is hosting a contest, and the whole town is talking about a talented new painter who is bound to win. But then an unknown person called "the Tattletale" sens Aldens notes and clues hinting that the artist may be an imposter and the Boxcar Children msut discover the truth behind the painting --and the Tattletale, too!