Under Paris

Sophia Assalas and her marine research team embark on an expedition near the Great Pacific garbage patch. Their mission is to locate Lilith, a tagged shortfin mako shark, indicating the start of a thrilling adventure.

Chris, Sophia's husband, leads a dive team consisting of Sam, Juan, and Tom. Together, they prepare for an underwater exploration that promises excitement and unexpected challenges.

As the team observes mako sharks hunting in packs, they are captivated by the beauty of nature. However, this peaceful observation soon turns tense as the expedition takes a dangerous turn.

The team successfully locates Lilith, but they quickly realize that she has grown significantly since her tagging. This encounter sets the stage for a perilous confrontation.

During an attempt to collect a blood sample, Chris faces fierce resistance from Lilith, resulting in a devastating tragedy. The loss of Chris and his team profoundly affects Sophia and marks a turning point in the story.

Years later, Sophia seeks solace at an aquarium in Paris, trying to rebuild her life. However, her past soon catches up with her when she learns unsettling news about Lilith.

Environmentalist Mika informs Sophia that Lilith's tracking beacon is still active and has traveled all the way to the River Seine. This revelation ignites a new mission to locate the shark amidst urban chaos.

A body marked by shark bites is discovered, raising alarms regarding Lilith's presence in the city. Police diver Adil approaches Sophia for help in tracking down this dangerous shark.

After reactivating the beacon, Sophia decides to join Adil's team to find Lilith. The urgency surrounding their mission grows as they prepare to dive into the depths of the Seine.

Mika draws Lilith towards her with a pulsing beacon in a quiet reservoir. In an act of faith, she enters the water, but tragically, Lilith attacks, resulting in the loss of several lives.

In the aftermath of the attack, Sophia and Adil discover that a juvenile shark has adapted to freshwater and is pregnant through parthenogenesis. This alarming development suggests more threats could be on the horizon.

Despite the rising danger, the Mayor insists on proceeding with a crucial triathlon, which poses greater risks to public safety. Sophia and Adil formulate a daring plan to lure Lilith out as the event approaches.

As swimmers take to the water in the triathlon, a massive school of juvenile sharks appears unexpectedly. The chaos results in numerous fatalities, complicating Sophia and Adil's efforts to neutralize Lilith.

In a hasty response to the chaos, military forces engage, igniting a series of underwater explosions. This reckless action leads to even more confusion and loss of life in the heart of Paris.

The film concludes with the unsettling realization that Lilith's offspring have infiltrated major cities worldwide, including Paris and New York. Sophia's darkest fears come true as civilization faces an unknowable threat.