"Have you ever had a glass of lemonade in front of you, but you happen to grab a glass of water instead?" Grant Achatz asks, sitting at a table in his celebrated Chicago restaurant, Alinea. "Your mind knows what it's supposed to taste like. You know what you're expecting it to taste like. And all of a sudden, there's nothing."

I'd seen Achatz pictured countless times, standing in Alinea's kitchen, incongruously baby-faced, at the pinnacle of chef-stardom. Then there were the clips from a local Chicago television station of him, hairless and haggard, during his grueling course of radiation and chemotherapy. (Without it, Achatz would have had a few months to live.) But the 33-year-old man in front of me, wearing a bright white chef's jacket and holding a plastic container half-full of cold coffee, is neither. He looks his age. He has a full head of thick tousled hair, a scraggly reddish moustache, and a patch of fuzz on his chin. On the left side of his neck is a faded four-inch scar.

It's typical for head and neck cancer patients who undergo radiation therapy to temporarily lose their sense of taste. But for Achatz, it seems a particularly cruel fate, one that completes the perfect irony of his sickness — a chef with cancer of the tongue. It tempts you to make out in his story the arc of a Greek tragedy, a man's towering ambition toppled by some vindictive god. What other explanation could there be? Achatz never smoked. He seemed healthy. The odds of this happening were somewhere in the one in a million ballpark. "Yeah, I had a 'What the fuck?' moment," Achatz says. "I felt like somebody was, like," — he smacks one hand with the other — "'Now let's see how ambitious you are.'"

A little over a year ago, Achatz was at the apex of his meteoric rise to culinary stardom. After the James Beard Foundation gave him its annual Rising Star award and Food & Wine magazine named him a Best New Chef for his cooking at Trio in Evanston, Illinois, he opened Alinea in 2005 with the goal of redefining fine dining. He blew bubbles with mozzarella, atomized shrimp, and dehydrated bacon. Achatz combined the precision and playfulness of his former boss Thomas Keller, the culinary deity behind The French Laundry and Per Se, with the almost hallucinogenic cooking of Spanish living legend Ferran Adrià. The result was an intensely engaging kind of haute cuisine, one that revived a childlike wonder in diners who had had it sapped by one too many tuna tartares. In the fall of 2006, Gourmet put out a list of America's 50 best restaurants — Alinea was number one. Soon, Achatz began work on an ambitious multimedia cookbook project. People started to wonder what the brilliant young chef would do next. Few knew that by last June, Achatz was in too much pain to eat solid foods. He had dropped 15 pounds and had trouble talking. His tongue had been overtaken by a tumor, a squamous cell carcinoma. It was Stage Four cancer — there is no Stage Five.