After the pirates' attack, the crew of the Pentokontors struggles to survive on a mysterious island. As Maximus and his team discover an abandoned Russian military base, Nazareth and Jota find signs of an unknown creature in the ocean. Amid sabotage, hidden secrets and a danger lurking in the dark, the group faces an uncertain fate.
           
   

Trapped in the depths, Monica and Jota see their oxygen running out. Nazareth risks her life to free them while at the base, next to Sonia, she discovers that Ray's body suffers an unprecedented mutation. Survival is complicated when America and Marco try to escape and a stranger breaks into the radio, destroying their only hope of rescue.