Five Weeks in a Balloon

The Jupiter, a manned balloon with a unicorn gondola, takes off in England during 1862 as Fergusson planned a dramatic demonstration. Sir Henry Vining and his treasurer scream in horror while Fergusson remains calm, signaling the audience that the craft is safe. The ascent ends with a successful flight, buttressing the inventor's reputation and setting the stage for the voyage.

After the near-disaster, the Royal Geographic Society balks at funding the African expedition. The Prime Minister orders Fergusson to defeat slave traders near the Volta River within six weeks and urges him to take O'Shay as a neutral witness. Sir Henry insists on being the expert on Africa and joins as the General to supervise.

In Zanzibar, Jacques spots O'Shay freeing slave girl Makia from traders and disrupting her sale. Local authorities demand their return to the owner, but Makia escapes and travels with the group aboard the Jupiter. The Duchess, a wild chimpanzee, is also adopted into the crew.

The balloon lands in a jungle, where Makia secretly joins the crew along with a wild chimp named Duchess. The team accommodates the new companion as they press toward Africa with renewed resolve. The group senses their journey will be more complicated with Makia aboard.

In the Arab city of Hezak, a Muslim priest proclaims O'Shay as the Moon God and the balloon as the moon, making the crew instant celebrities. Ahmed the slave trader arrives offering to sell a kidnapped American teacher, Susan Gale. The group flees with Susan aboard the balloon as the moon illusion fades.

The crew faces repeated mishaps as O'Shay takes blame for misfortunes, including drift into danger zones and lost anchors. They debate the need for two American witnesses, but eventually opt to hand O'Shay over to nomads until a sandstorm forces a reversal.

Near Timbuktu, the balloon lands in an oasis where they are captured by a patrol of the Sheik of Timbuktu. O'Shay, Jacques, and Ahmed disguise themselves to escape aboard the Jupiter, while Fergusson, Susan, and the General are imprisoned for infidels.

In Timbuktu, Makia is put up for sale as the others are imprisoned, but the trio buys her back from a slave trader. Makia warns them of the scheduled executions and the plan to escape, setting up the later rescue.

The crew flies the Jupiter to the high tower to save Fergusson, Susan, and the General as swordsmen attack. They defeat the guards but the balloon is pierced by a sword, causing a slow leak that threatens their mission.

Despite the leak, O'Shay convinces Fergusson to push on and fly through the night to reach the Volta River first. They hope to plant the flag and claim territory as slave traders close in.

As they near the Volta River, the slave traders shoot at the balloon. To gain lift and destroy the bridge, they climb to the crow's nest and release the gondola, wiping out most of the pursuers. The leader remains, escalating the danger.

The balloon crashes into a waterfall where the group swims to shore, with Ahmed riding the balloon as a raft. O'Shay returns for the flag and delivers it, earning back the group's respect and securing the mission's end. Ahmed kills the slave leader in a dagger duel, ensuring the flag's safe delivery.

Sir Henry admits he was wrong about Fergusson's plans, and the crew embraces as they celebrate the successful expedition. Romantic pairings form, with Jacques and Makia, Susan and O'Shay, and even Duchess finding a new chimp friend. The mission concludes with a triumphant return and acceptance of the dangers faced.