Julia Child's wartime spell in the Office of Strategic Services has always seemed the most intriguing chapter in the story of her evolution from the cocoon of her staid, soft-shoe Pasadena upbringing into the iconic French chef who revolutionized American cooking. Serving in that precursor of the CIA not only took her away from her native shores for the first time but also plunged her into two cultures about as different from what she was accustomed to as any you might find. Surely, it was no coincidence that India and China also boasted two of the world's greatest cuisines, so that amid all the culture shock there was also exposure to a panoply of spices and new ways of cooking.

How appropriate, then, that Jennet Conant, who has demonstrated her flair for bringing to life the odd interstices of World War II's intelligence services in "Tuxedo Park" and "The Irregulars," should now be training her sights on this time in Julia McWilliams' life, when she met Paul Child, the man who would give her that name — and so much more.

Conant doesn't disappoint in her picture of the whirlwind life of the OSS, created very much in the image of its founder, the maverick William J. Donovan. Her glimpses of how he overcame bureaucratic rivalries and turf wars are as exciting as her picture of life in the field, complete with dengue fever, cobras and scorpions. Unfortunately, it is buried in a welter of other material, and even more oddly, Julia and Paul Child are themselves overshadowed by other players in this dramatic period.

"A Covert Affair" begins with a coruscating account of how Paul Child was briefly caught up in Washington's McCarthyite madness in the mid-1950s while serving as a foreign service officer in Europe. But because he was rapidly cleared and suffered no severe damage, unlike so many others in this scoundrel time in our history, the episode seems overblown here. Worse still, since the cause of his trouble seems to have been Child's brief acquaintance with another OSS operative, Jane Foster, Conant immediately shifts the focus to Foster, where it largely remains. So much so that, amazingly, Julia and Paul Child seem at times to be relegated to the roles of bit players.

Foster is a quite a character — and what happened to her fascinating — but so are the Childs. When Conant can bother with them, what she has to say always piques our interest, even though it largely stays on the surface. The Childs were a truly unusual couple, deserving of the kind of in-depth analysis so well done by Katie Roiphe in her 2007 study, "Uncommon Arrangements." But what Conant does bother to tell us raises as many questions as it answers, tantalizing us when she returns repeatedly to Foster. Even Betty MacDonald, another OSS player, seems more to the fore than the Childs at times, seemingly because she was closer to the ever-intriguing Foster. We are repeatedly told how important Julia Child's work for the OSS was, but precious little is divulged about it, while we do hear a great deal about Foster's experiences in the field.

Conant has written a book full of fascinating material about wartime and postwar America and how they intersected, but those who turn to the book because of their interest in Julia Child will inevitably be disappointed. At more than 6 feet tall and blessed with that distinctive voice, Child had undeniable star quality, something she seems to have demonstrated in the OSS, in view of the crucial role she played there. It really doesn't suit her to play such a minor role in what is, after all, supposed to be her story.

Rubin is the author of "Sarah Gertrude Millin: A South African Life."