"The Memory of Eva Ryker" won't exactly be haunting anybody's dreams for months to come, or even for five minutes to come. But the CBS "special movie presentation," at 8 tonight on Channel 9, does provide three hours of fairly delectable and captivating idiocy.

The film, from a novel by Donald A. Stanwood, aspires toward lush, posh, pseudo-psychological romantic suspense as it unravels the spoos of nasty secrets locked away in Eva's brain. These involve an attempt to kidnap her at sea when she was a 5-year-old child, a plot foiled when a German torpedo sinks the good ship Queen Anne, taking, it is believed, $5 million worth of her daddy's smuggled diamonds to the bottom of the ocean with it.

By telling the story in an inside-out, humpty-dumpty way, screenwriter Laurence Heath makes it appear to be all but intoxicated with plot. Virtually nothing happens that isn't preposterous, and yet when the whole thing is over, you don't feel cheated. Just kidded.

Natalie Wood plays both the present-day grown-up Eva, and, in flashbacks, her mother, although there are no perceptible differences between one characterization and the other. The wardrobe does all the acting. When Wood rolls her eyes and swoons into what's supposed to be a catatonic trance brought on by traumatic nostalgia, she isn't that much more inexpressive than she is the rest of the time.

The hero of the piece is Robert Foxworth, who looks as though he is wearing more makeup than Wool and opens the film with the first of several certified hoots. He plays a Honolulu policeman circa 1961 who, confronted with a dead body in a garment bag, runs down the hall screaming "I've never seen anything so horrible!"

You wouldn't want this guy on the other end of "911."

Nine years later he has without any explanation metamorphosed into a magazine writer so successful he drives around Paris in a Rolls Royce Corniche. By kooky coincidence he is summoned to the home of the very rich and very mean William Ryker (Ralph Bellamy) who had a role in those Honolulu deaths, nine years earlier.

The director, Walter E. Grauman, has a high time with the ludicrous plot turns but also manages to let the movie go limp at a moment's notice, giving it a giddy, manic-depressive quality that proves, finally, more depressive than manic. This is the kind of movie in which most flashbacks are signaled with wobbly, watery dissolves and no self-respecting heroine can stomp out of a room without a flush of indignant music on the soundtrack. The score, by Richard La Salle, opens with one of those campy concerto title tunes suggesting an old Ross Hunter tearjerker, but "Eva Ryker" is actually an Irwin Allen production.

Allen comes skulking back to television (where he did things like "Voyage to the Bottom of the Sea") after a successful movie career ("The Poseidon Adventure," "The Towering Inferno") that recently has gone to pot ("The Swarm," "When Time Ran Out"). It's too bad television is something people are forever stepping down to instead of up to.

Little touches suggests the height of Allen's regard for the viewing audience. Almost immediately after the words "Australian Outback" are superimposed on a change of locale, we hear Roddy McDowall chirping, "Welcome to the Australian Outback!" And in the film's longest flashback we also see the screen's least convincing shipsink, as passengers jump overboard into water as turbulent as an August afternoon in Mr. Rogers' neighborhood.