THIS biography of Thailand's king Bhumibol Adulyadej falls into an unusual category of books. It is often inaccurate and written in a gushing style that is unlikely to be convincing even to those with little familiarity with the subject matter. About most subjects, it would not be worth a review.

Yet because of its subject, it is an interesting and in some respects valuable book. It addresses some key events of modern Thailand that most authors, foreign and Thai, gloss over because of their sensitivity to the issues concerned, not least some painful to the monarchy. Many of the thoughts expressed in William Stevenson's biography are clearly those of very senior Thais.

Stevenson claims to have had open access over an extended period to the king and to several people close to him. He also indicates access to Western intelligence sources, which would not be surprising given his previous books, including ''A Man Called Intrepid,'' about his namesake, Sir William Stephenson, director of British secret operations during World War II.

Though his new book is banned in Thailand, there is no reason to doubt that Stevenson had royal and other high-level access. The problem is the use he made of his sources.

The very subtitle of his book demonstrates a fundamental inability of author or publisher to grasp the importance of their endeavor. Though they admit its failings, they are content to have their work compared with a Hollywood version of a romanticized view of a fanciful portrait of Bhumibol's ancestor, the reforming 19th-century King Mongkut.

The often breathless prose rattles along without regard for checking facts against obvious known sources. It gives the impression of having been assembled from half-recollected talks with sources who in many cases were speaking colloquially or impressionistically.

A more serious author would have weighed individuals' comments and interpretations against known facts, or alternative views.

But Stevenson just gushes along, in the process often getting dates and relationships muddled up. Unsourced statements on key issues are legion.

Nonetheless, it has verisimilitude of a sort. Most important, it addresses the political and other circumstances surrounding the 1946 shooting death of the king's elder brother, King Anandar. Whether or not Stevenson's description of events is accurate, it evidently came from within the palace. It underlines the role of the pro-Japanese strongman Field Marshal Pibul Songkram in trying to pin the murder on the then prime minister, the democrat Pridi Banomyong.

Other issues that it touches on in interesting ways include the roles, and rivalries, of Western secret services in Thai politics during the post-1945 decolonization and early Cold War years. It offers some gossipy sidelights on the crown prince and on General Suchinda Kraprayoon's 1992 coup. The author's access to the king's remarkable mother, the late Princess Mother, is clear.

In sum it ought to be a revealing as well as sympathetic account of a man who has evolved into a king who has played a pivotal role in Thailand's modern transformation. But its style and inaccuracy demean the man it sets out to praise and devalue the insights that were offered to its author.