Nancy and her friends, George and Bess, are returning from a country carnival when they witness the explosion and burning of a beautiful country mansion. Fearing its occupants may be trapped in the blazing building, they rush to the rescue - and unexpectedly fund themselves confronted with a mystery that seems to be insoluble. The first clue, an anonymous diary, includes not only indecipherable handwriting, but puzzling technical drawings and chemical...

"What happened?" I asked, leaning against a folding chair as I tried to catch my breath. Julia glanced up at me coolly, and then reached for a box I hadn't noticed on the other side of the table. "Well, we received a disturbing package," she said. The box was about a foot square. Carefully angling it away from Carrie, Julia cracked the top of the box open. When I saw what was inside, my stomach roiled and I had to look away. Who would send something...

Nancy, Bess, and George are on an Alaskan cruise when things start to go awry