Soon after he purchases a dusty can of monster blood at the funky old toy store near his great-aunt Kathryn's house, Evan begins to notice some strange things happening to the people around him.
While staying with his weird great-aunt Kathryn, Evan visits a funky old store and buys a dusty can of monster blood. It's fun to play with at first, and Evan's dog, Trigger, likes it so much, he eats some!
But then Evan notices something weird about the green, slimy stuff. It seems to be growing.
And all that growing has given the monster blood a monstrous appetite...