A cosmic case of flying saucers, intergalactic intrigue and out-of-this-world romance launches Scooby-Doo! and the Mystery Inc., Gang into their most unearthly adventure ever.

Following her sister's disappearance, Jax and her niece Roki must stick together. Desperate to keep what's left of their family intact, Jax and Roki defy the law and hit the road on a journey to the Grand Nation Powwow in Oklahoma City.