Bones and Catson are visiting New York when the local police chief tracks them down. She explains that the city is being terrorised by a mysterious masked villain who is threatening the police with chaos if they don’t solve his riddles. The officers are struggling, and it’s lucky for them that the world’s greatest puzzle experts are in town. After thwarting a fiendish plot in Manhattan, Bones and Catson are...

Bones and Catson are visiting New York when the local police chief tracks them down. She explains that the city is being terrorised by a mysterious masked villain who is threatening the police with chaos if they don’t solve his riddles. The officers are struggling, and it’s lucky for them that the world’s greatest puzzle experts are in town. After thwarting a fiendish plot in Manhattan, Bones and Catson are hot on the heels of the mysterious criminal, on a chase that will take them to Niagara Falls and across the faces of the great dog presidents on Mount Ruffmore.

But there’s a greater mystery to solve while all this is going on. Who is the villain? And how can they unmask them?