The plot of the 39 episodes follows a young Spanish boy named Esteban who joins a voyage to the New World in search of the lost Seven Cities of Gold and his father.
[citation needed] English dubbed episodes also aired in the United Kingdom on Children's BBC from September 1st, 1986 to June 22nd, 1987,[1][2] and in Australia, on the public broadcaster ABC in 1986.
Mendoza sneaks Esteban aboard the sailing ship Esperanza, and once in the hold, he meets a kidnapped Inca girl named Zia who has a sun medallion nearly identical to his own.
Battered by the typhoon, the Esperanza breaks up and Captain Perez and the rest of the crew abandon ship leaving Mendoza, his two associates Pedro and Sancho, and the children to fend for themselves.
While exploring the island, Pedro and Sancho cross paths with a mysterious serpent-headed figure who Zia identifies as the Incan god Viracocha.
There, Zia translates a message in a knotted string called a quipu which leads to events that releases the Solaris – a golden sailing vessel.
The children set out to find Puna, Zia's home village, but to get there, they must go through a pass blocked by Pizarro's fortress which is built atop an underground temple.
Pasha reveals a secret escape route through a puzzle room, which once solved, melts a pillar of ice that collapses the temple and likewise brings down Pizarro's fortress.
Mendoza secretly tips off Esteban to the plan and Tao builds a giant flare which lights up the night sky and helps the Incas drive off the invaders.
Tao figures out that the marker points the way to the first city of gold, but before they can travel there, Esteban needs to have the sun symbol part of his medallion which Mendoza possesses.
Tao fashions a set of makeshift hand grenades out of clay pots with the left over gunpowder and buys some time to plan an escape.
The children meet back with Mendoza and set out to find the first City of Gold, but they come under attack by a hostile tribe of giant men called the Urubus.
After escaping they find an injured girl named Lana, who takes them to her village which floats on an island of reeds upon the waters of Lake Titicaca.
Eventually, the light of the setting sun leads them to a statue of Pachamama, and placing Esteban and Zia's medallions onto the goddess' breasts triggers a wall to open which reveals the first City of Gold.
The gold is only an illusion created by the glow of the setting sun on ordinary stone, but the children discover another treasure – a massive golden condor hidden inside a great temple.
With seconds before crashing, Esteban uses a sun disk he found in the temple to activate the controls and the incredible condor takes powered flight.
The next morning, the children examine the Nazca lines while Pedro and Sancho fiddle with the condor and discover a control stick in the shape of a cobra that can manually steer the bird.
As the condor flies over the Amazon River, a storm appears and cuts off the sunlight causing the bird to lose power and crash into the jungle.
The Amazon Queen praises Esteban for bringing out the sun, but Amoro still demands a sacrifice and chooses a young servant girl, named Morka.
The children learn that Amoro uses a sacred "rain mask" to foretell storms, but Tao discovers that the device is really a barometer made with knowledge from the Hiva people.
The children return the next morning to the room with the hieroglyphs and Tao finds writing hidden inside the eyes of the jade mask which leads them to a secret burial chamber.
Returning to the city, the children find that Mendoza, Pedro and Sancho have been taken prisoner by an unscrupulous Spanish explorer named Dr. Fernando la Guerra, and his assistant Marinche.
The children escape from the flooding temple on an altar made from a boat, and Kokapetl manages to steal back the valuable manuscript for Tao.
Esteban however, notices that Tao's wet manuscripts now reveal hidden symbols that spell out another message; a city of gold lies beyond a mountain called The Burning Shield.
They wake up later in a laboratory surrounded by the creatures and meet their leader Menator, who wants cells from the children to help slow down his people's aging process.
At the Olmec base, three new prisoners are brought to Menator; Dr. Guerra, Marinche and Tatiola, who offer to find the Golden Condor if they are set free.
Menator orders his craft to land and his men rush out to search the Condor for survivors, giving Esteban and Tao a chance to slip inside and overpower the Olmec pilots.
They are found by a mysterious high priest with a golden mask who claims that prophecy foretold of their coming, for they bear the medallions of the sun – the keys to the Cities of Gold.
When a gap is opened, Mendoza rushes inside and captures Kalmec setting Tao free, but once the gates are destroyed, Menator's machine flies in and reforms itself.
Earthquakes shake the City of Gold, and the high priest warns that the Olmec reactor must be shut down or it will burn a hole straight into the Earth.