Tortuous means twisting or complicated. "James Bond drove up a mountain road that was tortuous in its twists and turns. He had to stop the evil madman's plan for world domination, a plan so tortuous that even 007 himself could not understand it."
From Latin torquere "to twist," tortuous means something with twists and turns –– a path, an argument, a story. It is important not to confuse it with torturous, which means characterized by great pain. "The contemporary string quartet was tortuous in its tonal shifts, but only torturous at the point where the violinist ran her nails up and down a chalkboard."