Star Trek V: the Final Frontier (1989)

The crew of the Federation starship Enterprise is called to Nimbus III, the Planet of Intergalactic Peace. They are to negotiate in a case of kidnapping only to find out that the kidnapper is a relative of Spock. This man is possessed by his life long search for the planet Shaka-Ri which is supposed to be the source of all life. Together they begin to search for this mysterious planet.