The Grand Scream Of Things is a story about a boy named Andy Z who has one more chance to fully participate in everything Halloween (most importantly, to finally win 1st prize in the local costume contest- an accomplishment that has eluded him thus far) before he's considered too old to do so- but is forced to choose between this final opportunity to shine, and finding a young witch named Sandy who is revealed to him in a dream as losing her magic wand and being lost somewhere in Andyland.

He chooses begrudgingly to find the witch with the help of his faithful dog Reggie, chum Danger Dude, and alien “girl” friend (or is it girlfriend?) Pleadia. This quest for the witch takes Andy and friends through the “punkin” patch, to the school where teacher Jam Master Z gets them a cooking lesson from the Bakin’ Fools, and finally to the amusement park (with skater Blue The Rat) where they must enter the feared Bouncy House Of Horrors.

Andy does ultimately find Sandy Witch, but he also learns: it's not “the treats you eat” but “the friends you meet” that matter most.