After a traumatic divorce, Ricardo Adler sets out to discover how to achieve a fulfilling and lasting marriage. His search takes him to Rabbi Manis Friedman, who introduces him to Kabbalah's ancient secrets to attain the highest form of intimacy. The film portrays the dramatic transformation of Ricardo's new marriage, and the reactions of other couples to this revolutionary way to sexual connection. The Lost Key reveals forgotten wisdom that could inspire society to rediscover intimacy, one bedroom at a time.