My name is Chase Cooper, and this is my fourth diary as a 6th grade ninja. A few weeks have breezed by since my last entry, but things don't stay quiet at my school for long. The science fair is coming up, and everyone's been working super hard to get their projects finished on time. But at the beginning of the week, projects started disappearing only to be found completely destroyed. Did I mention the anonymous invitation I got that sent me on a...

"In the fourth and final book of this code-busting series, Marly, Sai, and Isla are back on the hunt. After their shocking discoveries on Summer Island, the Treasure Troop has one final set of clues to follow before reaching the end of their search. And now our trio must solve the toughest mystery of all: what really happened to Mr. Summerling?"--