Professor Poopsnagle's Steam Zeppelin (aka Professor Poopsnaggle and His Flying Zeppelin) is a children's television series, created as a spin-off of Secret Valley. It was produced by the Grundy Organisation from Australia, in association with Revcom Television from France, Katholieke Radio Omroep (KRO) from the Netherlands, and Televisión Española (TVE) from Spain. It was first aired in 1986 on the Nine Network in Australia, in 1987 on TVE 1 in Spain, and in 1989 on KRO in the Netherlands.

The series was also aired in Switzerland (TSI), Finland (1987), Greece (1988, ET1), France (1989, FR3), and Vietnam (1996, VTV3). In contrast to Secret Valley, which was a commercial failure in the United Kingdom when screened there in 1985, Professor Poopsnagle's Steam Zeppelin was hugely successful in the UK, where it was first broadcast in 1987 on the ITV network, and proved so popular that it was also later repeated on Channel 4 in both 1990 and 1998. The series still has a strong cult following in the United Kingdom today. The overall story is divided into 6 parts, each for a particular quest, with 4 episodes each. Some TV channels, such as ITV Anglia, therefore showed the series as TV movies of 90 minutes each. In this form the story is slightly abridged, cutting a few scenes that are present in cut for a half-hour slot.

Professor Poopsnagle, the holder of a vital scientific secret, has been abducted and his mysterious disappearance jeopardizes the world of science. His young grandson, who assists him in his research, secures the help of Professor Garcia, a long-standing colleague and friend of the scientist. Assisted by a group of children, spending their holidays in the Secret Valley Camp, Professor Garcia and the young boy build a flying bus. They set off in pursuit of the kidnappers and attempt, at the same time, to complete Poopsnagle's unfinished work. They are helped in their quest by a document that Garcia and the children gradually manage to decipher. But alas, there is a traitor in their midst passing information to the evil kidnappers of Professor Poopsnagle: Count Sator and his accomplice. However, against all odds, and throughout countless and often irresistibly amusing adventures, Professor Garcia and his young group of friends finally win the day. Time after time, the children show great courage and skill. Matt, the traitor, sees the error of his ways and they all live happily ever after.

Dr. Jose Calandre Garcia had been working on the theory of Mega- steam when he lost contact with his old friend Professor Poopsnagle. Determined to continue the work that Poopsnagle had originally begun, Garcia traveled to Australia in a hot air balloon in search of his old friend. Unbeknown to him, however, the evil, wealthy tycoon Count Sator had discovered his plan and sent his henchman Murk to shoot down the hot air balloon. Murk shot down the balloon, but the old doctor survived the crash and was rescued by some young children from a holiday camp in Secret Valley. When they heard the doctor's story of why he had come to Australia, they decided to help him in his quest to find the 6 minerals of Megasteam.

The only contact with Poopsnagle that remained was a telephone number. When Garcia called the number, he got a message machine. He left a message for his old friend to contact him at the Secret Valley holiday camp. Instead of Poopsnagle, Garcia was surprised when a young boy of 12 years old turned up instead. It was none other than Poopsnagle's grandson, Peter. Together they resolved to build a flying bus which was originally designed by Professor Poopsnagle to help them in their search for the minerals.

In a nearby deserted town, the children gathered all sorts of junk to help make the flying contraption. Luckily, they found the wreck of an old bus as the basis of the machine. With the help of the children, and following Poopsnagle's plan, the bus was eventually completed, and based on steam power it was able to rise into the sky and fly at will. Count Sator, however, sent another henchman called Willie Dingle (an intelligent but clumsy and accident-prone electronics expert, who Sator had employed to build, operate and maintain a complex radio communication and computer system) to spy on the children; whilst Sator and Murk were persistent in trying to sabotage Poopsnagle and Garcia's plans, Dingle was a more reluctant accomplice, who was repeatedly bullied and intimidated into co-operation by Sator and Murk. Within the ranks of the children, Sator also commissioned a young boy named Matt to keep him informed.

Poopsnagle's grandson Peter also had an ancient parchment that his grandfather had left him, and on the parchment was a cryptogram written in Latin. After the cryptogram had been decoded, it was only a matter of time before they found the first golden salamander.

The golden salamanders had been buried long ago to indicate where each mineral could be found. After the first one was found, the cryptogram on it would lead the children and the doctor to the next one. What they had to do in each case was to decipher the cryptogram on each salamander. The first one led them to a cave not far from Secret Valley, where after being caught in a mine shaft and surviving a gas explosion, they were able to find their way down the shaft and into an unknown valley where they found the second salamander and the first mineral.