This is volume 3 of the series of books with the toughest and deadliest Killer Sudoku puzzles. All puzzles in this volume are new, previously unpublished. It contains only puzzles of the 3 hardest levels of difficulty: BRAIN, IQ and INSANE, with addition of a few puzzles of an even more fiendish kind - Zero Killer Sudokus. Contents: 40 BRAIN (5 diagonal) 50 IQ! (5 diagonal) 10 ZERO (including 5 ZERO INSANE) 11 totally INSANE! For a total of 111 most difficult Killer Sudoku puzzles! By no means is this a book for a novice Killer Sudoku solver. It is intended only for the most experienced and most persistent of those who are already masters at solving Sudokus with sums. So... are you up for this challenge?