The Mystery of the Third Planet

The Mystery of the Third Planet Тайна третьей планеты
DVD cover (Krupnyy Plan)
Directed by	Roman Kachanov
Written by	Kir Bulychov (story & screenplay)
Starring	Olga Gromova Yuri Andreyev Vladimir Druzhnikov Vladimir Kenigson Vasily Livanov Rina Zelyonaya
Music by	Aleksandr Zatsepin
Edited by	Nadezhda Treshcheva Olga Vasilenko
Distributed by	Soyuzmultfilm (USSR) Jambre Pictures (U.S. 1981-1985), Touchstone Pictures (U.S. re-release, 1985)
Release date	1981 (1981) (USSR)
Running time	50 minutes (original version)
Country	Soviet Union
Language	Russian

The Mystery of the Third Planet (Russian: Тайна третьей планеты, Tayna tretyey planety), aka The Secret of the Third Planet is a 1981 Soviet traditionally animated feature film directed by Roman Kachanov and produced by the Soyuzmultfilm studio in Moscow. It is based on a children's science fiction novella "Alice's Travel" by Kir Bulychov, from Alisa (Alice) Selezneva book series.

The movie is considered a cult classic in Russia, it was included in various top list of animated films and science fiction films. A shortened novelisation of the film was written by Bulychov himself, a diafilm and a number of video games were based on The Mystery of the Third Planet, and spiritual successor film Alice's Birthday was released in 2009.

As part of an expedition from Earth on the ship "Pegas", Captain Zelyonyy, Professor Seleznyov and his daughter Alice Selezneva search for new animal species for Moscow Zoo. On the advice of the archeologist Gromozeka they look for with the help of doctor Verkhovtsev, the director of the museum of Two Captains, but the doctor behaves suspiciously: doesn't show them diaries of captains and starts spying on the expedition. On the planet Blukthey make some valuable purchases, among them a Chatterer — the bird belonging to the missing captain Kim. A suspicious fat man, Merry Fellow U, tries to steal a bird. Having listened to the speech of the Chatterer, the crew of "Pegas" heads for system of the Jellyfish. On the road heroes rescue robots of the planet of Shelezyak from diamond dust, admixed in greasing.