For years, natural scientists have been trying to understand a mysterious phenomenon which was happening off the coasts of the Reunion island. Once the natural basin for groups of whales and green turtles, the waters around the island were surprisingly deserted by them. But now, to their astonishment, natural experts have seen these animals coming back. But why are green turtles and whales coming back to the Reunion waters? Naturalists have recently been teaming up in order to understand this unexpected return. They will be observing a whale calf and its mother on a journey to the Antarctic. At the same time, they will be following a young turtle on its way back to its birthplace. The journey should help them to discover any possible new route and to comprehend the reasons of the shift in the animals’ behavior. By combining amazing underwater and spectacular airborne images together with CGI illustrations of routes and possible influencing factors, this scientific /nature one-off will capture incredible rarely-seen behaviours and probably contribute to the solution of an enigma.