by Ella MacMillan (Contribution by), Robert MacMillan (Author)

Are these the most difficult Killer Sudoku puzzles in the known universe? A compendium of 200 puzzles, strictly for experts. 40 3-star puzzles to warm you up. 80 4-star puzzles to click into top gear. Then 80 5-star puzzles when you're in Killer Sudoku overdrive. Finish them all and justify your place among Killer Sudoku grandmasters.