The Hidden Staircase - Mildred Benson, Carolyn Keene
It's quite strange that I read Nancy Drew and not the Hardy Boys. I've been thinking a lot about all the old mysteries I read when I was younger lately, and can distinctly remember that this was the best one I read. Why? Because there was a part with someone in a gorilla mask or something and it scared the living dogs#*t out of me. 5/5