Brains und Tin-Tin starten einen Tauchausflug zu einem versunkenen Tempel, der verborgen in den Fluten des Lake Anasta liegt. Dummerweise sucht Hood auch nach dem Tempel und seinem Schatz. Er nutzt die Gelegenheit, entführt die beiden und versucht erneut an die Geheimnisse der Thunderbirds zu gelangen ...
Taking a much-needed break from their rigorous schedules, Brains and Tin Tin set off on a working vacation in the Middle East, where they'll be assisting a renowned professor with the recovery of hidden treasure from the bottom of a lake.
As our two intrepid heroes embark on their journey, Tin Tin's father, Kyrano, expresses his uneasiness to Jeff Tracy concerning the expedition. ""A beautiful lake miles and miles from anywhere,"" Jeff says. ""What could be safer?""
Kyrano's fears are justified, however, as his evil half-brother, the Hood, has once again compelled him to reveal details about International Rescue's activities.
Making a valuable discovery during their very first dive, Brains and Tin Tin anxiously await the next day's explorations. Unfortunately, they may not last that long, as the Hood infiltrates their camp and hypnotizes them.
When morning comes, Tin Tin is slumped over in a chair and the professor is clearly injured and sprawled out on the floor of their trashed caravan.
Brains et Tin-tin partent en expédition au lac Anasta afin de retrouver le trésor qui se trouve au fond de celui-ci. Dans le même temps, The Hood les surveille depuis son sous-marin. Brains décide de plonger afin de retrouver le trésor, mais se fait piéger au fond. Les Sentinelles de l'air interviennent, mais auront-elles le temps de sauver Brain et le trésor ?
Brains e Tin-Tin partono per una spedizione in Medio Oriente alla ricerca di un tesoro sommerso. Hood scopre la missione, si infiltra nell'accampamento e li ipnotizza, trasformando la ricerca archeologica in un'emergenza.
Tin-Tin en Brains gaan met professor Blakely op een expeditie naar het Anastameer om een verzonken tempel te onderzoeken. The Hood heeft ook interesse in de rijkdommen die in deze tempel zouden liggen en volgt hen.
