With “Guardians of the Galaxy,” the Disney-owned Marvel Studios introduces a new film franchise that’s off to a great start. Lighthearted in spirit and quick on its feet, the two-hour sci-fi adventure flies by in a whoosh of nimble action and colorful characters.

Five unexpected heroes join together in a mission to save their imperiled galaxy, though this gang of misfits seems unlikely to save anything. That’s part of the fun.

The previously unaligned guardians unite after handsome young adventurer Peter Quill is hired to find an orb for an unknown buyer. Quill doesn’t know it, but the object inside the orb can destroy entire worlds.

When Quill locates the orb on an abandoned planet, he’s instantly attacked by the forces of Ronan. An evil, powerful being, Ronan takes pleasure in killing, both on a planetwide scale and up close and personal.

Quill escapes from Ronan’s hunting party and travels to the planet Xandar, where he plans to deliver the orb to a middleman. Apprehended on Xander by Nova Corps, the military force charged with policing the galaxy, Quill is thrown in a prison in space with his future fellow guardians of the galaxy.

Like “Star Trek,” “Stars Wars” and other enduring sci-fi adventures, “Guardians of the Galaxy” succeeds most of all through its characters. Quill has a sad backstory that begins on Earth. He keeps the past with him via a vintage Sony Walkman player and a collection of cassette tapes containing hits songs of the late 20th century.

Most of the other guardians have tragic pasts, too, including displacement and the loss of loved ones.

Zoe Saldana plays Gamora, a green-skinned humanoid whose body has been redesigned to kill. Former WWE star Dave Bautista is Drax, a physically imposing, tattoo-covered humanoid who’s determined to avenge the murder of his wife and child.

Two mostly computer-animated characters — Rocket, a genetically altered, cybernetically enhanced raccoon, and Rocket’s friend, a humanoid tree creature named Groot — steal scenes from their somewhat less exotic fellow guardians.

As cute as a talking, walking upright raccoon may be, the aggressive Rocket is not so cuddly. Bradley Cooper, an Oscar nominee for his roles in “American Hustle” and “Silver Linings Playbook,” provides a smart-guy voice for the verbally prolific Rocket.

Cooper’s voice performance, combined with computer animation that places Rocket in the middle of the action, makes the little furry guy larger than life. Two life-sized versions of Rocket plus a bust of Groot were used on the movie’s sets as reference points for the other actors.

Groot, voice by Vin Diesel, and Rocket make a great pair. Even though the tree man’s vocabulary consists of only three words — “I am Groot” — Diesel and the computer animators inject multitude meanings in that one phrase.

The deep cast of “Guardians of the Galaxy” extends to John C. Reilly as a Nova Corps officer: Oscar-nominee Glenn Close as Nova Corps’ leader; Karen Gillan (“Doctor Who”) as Ronan’s henchwoman, Nebula; and an especially colorful, down home in outer space performance by Michael Rooker (“The Walking Dead”) as space scavenger Yondu.

Charming characters, high-flying fun and quick-tempo adventure guarantee that “Guardians of the Galaxy” will be back. It’s a Marvelous time at the movies.