Heartbroken Lana Wood is pleading to Christopher Walken to expose the "hateful lies" and reveal the truth about what really happened the night Natalie Wood died!

Breaking Celebrity News has exclusively obtained a letter that Natalie's distraught sister addressed to the Oscar-winning actor — whose testimony could solve the mystery of the screen legend's bizarre death once and for all.

Walken, now 72, appeared with Natalie in the sci-fi film Brainstorm and was partying with his co-star and her husband, Robert Wagner, aboard the yacht "Splendour" on Nov. 28, 1981 — the night before Natalie, 43, was found drowned in the waters off Catalina Island, Calif. And now Lana is appealing to Walken to tell what he knows.