Evan is sent to stay with his strange Great-Aunt Kathryn while his parents look for a house. He didn't want to, but his parents said they had no choice.Evan eventually meets a girl, Andy, who soon becomes his friend. In town they go to the local toy store and Evan finds this can of stuff called Monster Blood.Andy and Evan have fun playing with the Monster Blood at first, but soon it starts acting strange -- it seems to be growing and the friends have no idea what to do.This one was quite good. I thought the characters were good as well. I really liked Kathryn and I knew there was a different side to her, but you just wouldn't see it until later.I thought this was better than the second book in the series. I really enjoyed it.