Frank Mars and Milton Hershey started family businesses that became two of America's most familiar corporations. Former Washington Post reporter Joel GlÎnn Brenner spent nine years researching them, and the story of their bitter rivalry for the world of sweets makes riveting reading.

Mars Inc. was begun by the founder as a last-ditch effort after many failures, and later taken over and grown to prominence by his estranged son, who had started a rival candy concern near London. Today an $18-billion colossus, the world's largest candy company is owned and run by three Mars grandchildren in a style somewhere between idiosyncratic and bizarre. The billionaire owners, for instance, work 70-hour weeks, punch time clocks and have no private offices.

Hershey is only a little less strange. Its chocolate, we learn, has an off flavor that makes it intolerable to non-U.S. palates. The company's refusal to change its formula has kept it home while Mars, which started later and more slowly, has gobbled up the global market. Though no longer a family concern ‚ Milton Hershey died childless ‚ the controlling shareholder is a foundation whose sole beneficiary is a children's home.

The Emperors of Chocolate is a tale of triumph and tragedy, weirdness and warmth. No one who reads it will bite into a Snickers or Hershey bar without thinking of the strange saga behind them both.