MYSTERIOUS PLANET, initially created by Jean-Claude Forest in 1971, and reprinted several times since, is a space fantasy retelling of JULES VERNE's classic tale by the creator of the world-famous BARBARELLA and HYPOCRITE..

In the Year 4880, an ion storm forces a spaceship to crash-land on an uncharted planet in the Constellation of the Verne. Aboard the ship are its pilot, the grouchy but tender-hearted BRISE-BISE, DOCTOR ALIZARINE, an exobiologist from YOLANDA, the zoo planet, his man-servant BRABBIT (a rabbit-like alien), JOHN PARAGRAPH, reporter extraordinaire and writer of adventure novels and LITTLE PAUL, a teenage space orphan.

The mysterious planet is a vast ocean, except for one very large island shaped as a question mark. The Castaways dub it the ISLAND OF WYE.

First, ALIZARINE is believed lost at sea during the crash. Later, they find that he's been mysteriously dragged out of the water and to a safe refuge. The Castaways then discover a 1000-foot tall tree -- which they christen the MIDNIGHT TREE -- which occupies the entire northern section of the Island. They decide to climb it.

Inside the MIDNIGHT TREE is an entire ecosystem, with its own climate, fauna, etc. The Castaways learn to survive, foraging food from the tree and getting acquainted with the strange animals who live in it. They even find a sweet water lake, but are attacked by a monster which is mysteriously slain by an invisible force. Later, they build a shelter in a vast tree cavern, using makeshift resources and equipment they find in the hull of their wrecked ship, and which BRISE-BISE swears wasn't there before. LITTLE PAUL comes up with the theory of the WATCHER, a mysterious presence who is helping them.

Time passes. One day, as they explore, they are attacked by KALAMINES, ancient war machines stranded on the Island. Again, they are rescued in the nick of time, but this time, they discover who their mysterious rescuer is: a service droid, VAUCANSON, allegedly abandoned on the Island by space traders because he'd been accidentally irradiated. VAUCANSON, injured by the KALAMINES, "dies" without revealing its secrets. Was he really the WATCHER?

More time passes. Using the mysterious supplies, BRISE-BISE has managed to build a flying machine. One day, PAUL sees smoke coming from the dot of the question mark at the other end of the Island. Leaving ALIZARINE and BRABBIT behind, they fly there and, after some exploration, discover a teenage "wild girl" -- but not the identity of the person who started the smoke device. The girl turns out to be RUSTY, daughter of notorious space prate IRONJAW, who stranded her on the Island because she refused to become a pirate. LITTLE PAUL and RUSTY quickly become attracted to each other.

As they return to the MIDNIGHT TREE, a fierce storm erupts, and they become lost in the darkness. Eventually, BRISE-BISE sees a light which enables him to safely land near the tree. But it turns out that ALIZARINE did not light it. Is the WATCHER back?

Soon afterwards, they spot IRONJAW's heavily armed pirate ship approaching. He has come back for RUSTY. With their usual resourcefulness, the Castaways make maximum use of the Island's natural resources to wage a successful guerrilla war against the pirates. IRONJAW bombards the Tree. RUSTY is captured by her father, but rescued by LITTLE PAUL. The teenagers manage to plant a bomb aboard the pirate ship, which is destroyed. Was it really the bomb, or one more intervention by the mysterious WATCHER?

However, the pirates survive and gain a foothold on the island. Later, LITTLE PAUL is wounded in an ambush. As he lies dying, he is taken away by a mysterious presence who has come through a secret, metal doorway, hidden deep inside the cavern -- at last, proof of the WATCHER's existence.

The Castaways don't have time to investigate what lies behind the door, as the pirates launch another attack. And RUSTY (who, unlike LITTLE PAUL, never believed in the WATCHER) is convinced her father kidnapped LITTLE PAUL.

A final battle opposes the Castaways and the pirates on the branches of the Midnight Tree. Through ruse and superior knowledge of the terrain, the Castaways trick the pirates and win. All the pirates fall to their deaths, except IRONJAW, who's taken prisoner.

Meanwhile, at the Castaways' base camp, PAUL has returned, fully cured, in the arms of an android (MARGUERITE). They follow her back through the doorway and into a series of secret passages leading deep below the very roots of the Midnight Tree. There, they discover a secret space dock -- and a ship.

Aboard it, they finally meet the mysterious WATCHER, who's secretly helped them all along. It is -- BARBARELLA, the legendary space outlaw who'd been hiding from galactic justice on this island in a state of suspended animation, waiting for the "heat" to die down. She awoke when the Castaways arrived.

The Castaways tell BARBARELLA it's now safe to return to Human Space -- especially after having captured the notorious IRONJAW -- and together, they leave the MYSTERIOUS PLANET.