Grades 5-8--Once again, P. C. and his friend Mackenzie stumble into a murder and onto the murderer. When their nasty calculus teacher at Columbia University is pinned to the blackboard with an arrow shot from a crossbow, the two friends begin to investigate their eclectic collection of classmates. Some attend the college, but others, like Mac and P. C., are high school students taking advanced classes. A visit to a medieval weaponry collector's makeshift torture chamber, a careening taxi ride across New York City, and the final, hair-raising chase through the darkened halls of the university add excitement to this basic whodunit. The audience for this book is a little unclear. The main characters are juniors and are appropriately pictured (if a bit unrealistically perfect) on the cover, but the book design and story are clearly for younger students. The plot is simplistic and is of the cookie-cutter variety. Upper-elementary-school fans of series mysteries should enjoy it and perhaps reluctant readers in the upper grades would also find it appealing, but they may take issue with the large paperback format.