In this supernatural thriller, an ominous cloud meets a supersized wave during a surfing competition, engulfing the participants in one fell swoop. When the cloud dissipates and the water settles, the surfers are nowhere to be seen. Five hours later, they reappear safe and sound – but with no recollection of their disappearance.

Things are back to normal in Brizan... in appearance only. The surviving surfers discover they have gained strange powers. Young Thomas now has perfect eyesight. High school student Mathieu can now cure his father's patients better than his father ever has. Surf champion Max finds out he can hold his breath underwater for an extraordinary amount of time. Lena too seems changed, and is now trying to reconnect with Ben and his daughter Yael. Ben discovers, stunned, that surfers seem strangely connected to the cloud...

Brizan is in a state of high alert. The cloud caused a tidal wave that destroyed the lighthouse, and the small town is now split in half by the water. Lena sees strange coincidences with her own dream. While the locals start to panic, Faust Ketchak sees in this phenomenon a revolt of Nature, a punishment against humanity's destructive behaviour. Meanwhile, Lena and Ben uncover significant pollution on the Brizan site run by Julien. Sick with worry, Lena suffers from a mysterious illness.

Surfers who have lost consciousness after the launch of the drone finally wake up... all except Romain. When Ben returns home, upset by the death of the teenager, Lena finally decides to reveal her pregnancy. In the small town, everyone is shocked by the death of Romain, especially his friends. Yet life must go on – the cloud has vanished, the threat now seems over... Thomas then confides to Ben that the cloud has actually returned, and he's the only one who can see it: it is now covering the entire city... and it won't be long until it strikes again.

Marianne and Ben are terrified to discover they are the victims, like most of the population, of a very serious and inexplicable intoxication. Only the ten surfers seem to have been mysteriously spared. The city is quarantined by the authorities. The life of the Brizannais is now at stake; they realise only too late that Ben and Faust Ketchak were right and all make the connection with the cloud that has infiltrated the city the previous night. Mad with worry, Ben continues to search for answers. He discovers that the solution could come from the surfers themselves.