One starting book for the whole Second World War

If a reader wants one book covering the whole Second World War, where should they start?

How the War Was Won by Phillips Payson O'Brien is a useful broad starting point, although its interpretations should still be tested against other works.

A single-volume history must compress campaigns, institutions, economies, and several theaters into one argument. Phillips Payson O'Brien's How the War Was Won is recommended as a useful research starting point across the conflict. The recommendation comes with explicit disagreement about some of the book's conclusions. It offers an entry into the debate and cannot replace wider reading with one synthesis.