A little island called Bonaire, one of the Netherlands Antilles just off the coast of Venezuela, appears amply to deserve its name. "Wilson's Reward," a one-hour adaptation of a Somerset Maugham story, was filmed there, and the aire looks very bon indeed. Seldom has a setting so completely upstaged a tale.

Of course, the way actor and barkeep Patrick O'Neal has directed this thing, it could have been upstaged by the outskirts of Fairlawn, N.J. Bonaire, as photographed by Larry Pizer, looks serene, untroubled, flat, warm and heavenly, the perfect place to go and sit and do nothing, which is about what O'Neal and his actors did.

In the film, at 10 tonight on Channel 20, Maugham's story -- almost a reversal of "Rain" -- about a lecherous drunk's miraculous reform at the hands of a virginal lady missionary, never quite takes hold. The characters have no definition, conversations don't connect, and the filmmakers appear to have barely touched, much less gotten a grip on, the material. Essentially what you get, in addition to the glorious picture postcards, is an anecdote stretched thinner than a hummingbird's eyelash.

Sandy Dennis does another of her neurotic twitch numbers as the only woman in the story and surely the least galvanizing missionary in the history of missions. Gerald S. O'Loughlin, the cop show veteran, manages to exhibit even less charisma as the drunken Wilson. And while Fred Morsell exudes considerable charm as the privileged, worldly governor of the village (supposedly in the West Indies), O'Neal, and scriptwriter Bernard Eismann, have simply stranded him, perhaps in an effort to prove that some men are islands after all.

Only two touches seem appreciably Maughamy. When Dennis trots off to another isle to perform an appendectomy, she chases the resident tribal priest away, but later, as she prays aloud over the boy, he appears at the window behind her and defiantly resumes his potion-spritzing, unbenownst to her. And at the fade-out, the characters mime an operatic "Adio" (the soundtrack is riddled with Rossini) that is as blissfully balmy as the blue-green Caribbean onto which the happy couple sets sail.