Nancy encounters a mysterious saleswoman in a perfume shop, a curious man on the train, and then finds herself trying to decipher a strange code.

"When best friends Abbi and Skylar witness a clandestine meeting between a mysterious woman and someone in a dark van, they're thrilled. Finally, a mystery to spice up the summer! Who could these people be? Why are they meeting? Are they spies? Criminals? The two girls are determined to find out. But then a local woman goes missing and is found dead in the woods. And Abbi and Skylar realize that their detective work could hold the keys to solving...