Tortuous [adjective]: Twisting, having sudden or sharp turns and corners.
Because it sounds so much like torturous, most people confuse the two. While something can be torturous, it doesn't also mean that it's tortuous (or vice-versa). For instance, a book with many twists and turns can be tortuous, but quite an exciting and engaging read. A torturous book, on the other hand, is just unpleasant to read.