Alisa Seleznyova, her father professor Seleznyov, and the ship's captain Zeleniy are travelling in space on the Pegasus.

They meet their old friend alien archaeologist Gromozeka, who's just discovered an empty space ship called Black Wanderer all inhabitants of which died.

At some point, a slave that labored in the Black Wanderer sacrificed himself and broke a lilac ball, which caused the space pirates to wipe themselves out.

The only chance to save the Earth is to travel 26000 years back in time - to the epoch when witches, dragons and magicians lived along with usual people.

They stop them from feasting on a human child named Gerasik who has seen the Black Wanderer's landing craft (which looks like a giant egg).

Uuu-Uuu-Uuh flies by on a magic carpet looking for Alisa, but is attacked by the pirates and escapes using his invisibility cap.

While discussing on how to dispose it, Uuu-Uuu-Uuh also travels to the future using magic and throws the lilac ball into the sun, disintegrating the virus.