Gluttons for punishment rejoice! The popular series of ultrahard sudoku is back. Just when it seemed safe to go back into the puzzle section of the bookstore ... here comes another collection of the hardest sudoku known to humankind. The newest four volumes of this bestselling series range from Level 1 to Level 4, increasing in difficulty as they go. In Level 3, solvers will encounter 242 puzzles requiring some of the trickiest expert techniques. It might seem unbelievable that harder sudoku than these exist, but they do: in Level 4!