Calculus Mysteries and Thrillers consists of eleven mathematics projects based on introductory single-variable calculus, together with some guidance on how to make use of them. Each project is presented as an amusing short story. In many of them a group of undergraduate mathematics students, formed into a consulting company called Math Iz Us, is hired to solve mathematical problems brought to them by clients. The problems solved include: helping to prosecute an accused pool shark, defending a driver accused of speeding, assisting a hockey coach in making his star forward a more effective goal scorer, and advising a pirate captain on how to divide a gold-plated goose-egg fairly among his crew. In each problem, the problem solvers are required to present to their client a detailed written report of their findings. Thus, students must produce and analyze accurate mathematical models of complex, verbally presented real life situations, and write a clear technical account of their solution. Instructors who are looking for problems that are novel, interesting, and several levels more complex than the typical text book word problem will find them in this book. It will be of particular value to instructors who wish to combine training in applications of calculus with training in technical writing. The complexity of the problems makes them suitable for use as group projects. The calculus concepts on which the problems are based include: tangent and normal lines, optimization by use of critical points, inverse trig functions, volumes of solids, surface area integrals, and modeling economic concepts using definite integrals. Although a few ideas from physics and economics are used in the problems, no prior knowledge of these fields is required.