"Sidney Sheldon's Bloodline" (what a fascinating title!) squanders a formidable international cast on a piece of material you wish the cat would drag back out.

"Bloodline" is surely one of the most perfunctory murder mysteries ever committed to foolscap. Not a bloody thing ever develops. After lining up the characters, Sheldon doggedly shifts scenes, suspects and red herrings until accumulating enough pages to call it a hefty read.

Having emerged as "Mr. Best Seller," Sheldon is now allowed to insinuate his name in the titles.His ponderously junky prose style is also somehow respected in the process of adaptation. As a result, the storytelling pace slows down while a maximum of stale situations and exhibitionistic teases pile up.

The big tease in "Bloodline" is snuff movies. While the plot deals with a murder scheme aimed at the heiress to an international pharmaceutical and chemical corporation, the murderer also stages snuff movies on the side, leaving vermilion ribbons around the necks of the victims. This subplot has no organic relationship to the plot. It simply relieves the prevailing drudgery by interjecting a kinky thrill at regular intervals.

Audrey Hepburn, always welcome but compelled to act tiresomely fretful, is cast as th heiress, a shy, retiring paleontologist who reluctantly becomes a captain of industry. Her father, the founder of the corporation, has died under suspicious circumstances. When she resolves to keep the firm in the family instead of going public and selling out, her own her life is repeatedly threatened.

The most glaring suspects are the heroine's cousins and in-laws, who also happen to be board members. All are in need of ready cash for one scandalous reason or another. James Mason, a Conservative MP, is faced with the crippling gambling debts of wife Michelle Phillips, Omar Sharir, an overextended playboy married to family member Irene Papas, is being blackmailed by his angry mistress, Claudia Mori. Maurice Ronet, another weakling son-in-law, has been embezzling the fortune of his domineering, insatiable wife, Romy Schneider.

Beatrice Straight, the late chairman's secretary, and Ben Gazzara, his troubleshooter, are also subject to suspicion, though Straight tends to eliminate herself prematurely by flaring her eyes with sinister significance and regularity. The mystery is supposedly in the experienced hands of a rumpled, shambling Zurich policeman, Gert Froebe, who spends a good deal of time consulting his computers.

The maddening thing about the plot is that any suspect would, indeed, be as good as any other. Sheldon's murder story doesn't hinge on clues or psychology. It shambles along, much like Inspector Froebe, until an arbitrary culprit is chosen from the bunch.

Screenwriter Laird Koenig had jettisoned some of Sheldon's inventory spare characters and redundant episodes and slipped in some intentional humor. Nevertheless, the original novel acts like a ball and chain on the film version. For some inexplicable reason the continuity is even slowed down to accomodate flashbacks depicting the late founder's boyhood, although these episodes are obviously superfluous and awkwardly intergrad.

Trying fro more effective associations, director Terence Young stages several of Hepburn's scenes against locales or settings designed to recall her earlier films, including the success they enjoyed together, "Wait Until Dark." Unfortunately, picking up on these hints makes you wish you were seeing "Wait Until Dark" or "Charade" or "Breakfast at Tiffany's."

Hepburn looks more attractive in this film than she did in "Robin and Marian." It's easier to imagine her continuing her career through middle age, although one feels affronted at the drivel she's obliged to play in "Bloodline."

Hepburn and her co-stars have accumulated enough credit over the years to keep us watching this unworthy vehicle. Their presence even lends an incongruous class to the enterprise, in the same respect that satiny gowns lend it class when Freddie Young's lighting is at its richest. But why should they have to play junk this unworthy?

It's not as if "Bloodline" has to rise to the level of "The Carpetbaggers." CAPTION: Picture, Audrey Hepburn and Ben Gazzara, center.