In the year 2027, a devastating crisis of global female infertility has unraveled the fabric of society, leading to chaos and despair. The United Kingdom, now the last bastion of stability, is inundated with asylum seekers and has devolved into a militarized police state where immigrants are relentlessly hunted and detained. Amidst this grim reality, former activist turned disenchanted bureaucrat Theo Faron (Clive Owen) finds himself ensnared by a group of immigrant rights activists known as "The Fishes." He is confronted by the group’s leader, his estranged wife Julian Taylor (Julianne Moore), with whom he shares a painful past rooted in the loss of their son to a devastating flu pandemic back in 2008.
Julian implores Theo to assist her in securing transit papers for a young black female refugee named Kee (portrayed by Clare-Hope Ashitey). She offers Theo a financial incentive to facilitate the process, convincing him to reach out to his cousin Nigel (Danny Huston), a government minister. However, the catch is that the bearer must accompany Kee, compelling Theo to undertake the perilous journey with her in exchange for a more substantial reward. They are joined by Luke (Chiwetel Ejiofor), a member of The Fishes, and Miriam (Pam Ferris), a former midwife. As they make their way to the coast for a boat that promises escape, they encounter an armed militia, leading to a harrowing ambush where Julian is tragically shot.
In the aftermath of Julian's death, Kee reveals to Theo a shocking truth: she is pregnant, a piece of critical information Julian had urged her to share only with him. While initially planning to deliver Kee to the "Human Project," a rumored scientific organization in the Azores focused on rekindling fertility, conflict arises as Luke persuades Kee to stay with them. In a twist of fate, Theo uncovers a treacherous plot involving The Fishes, learning that Julian's demise was a deliberate act orchestrated to utilize Kee's child as a political symbol amid their revolutionary endeavors.
Determined to protect Kee, Theo enacts a daring escape plan with the help of his old hippie friend, Jasper Palmer (Michael Caine), a former cartoonist. They plan to board the ship Tomorrow, which will arrive off the coast near a refugee camp. Time is critical as they navigate the dangers of the camp, leading to an intense showdown with the Fishes. As chaos erupts, Kee gives birth to a baby girl in a makeshift shelter provided by Marichka (Oana Pellea), just as war erupts between the military and the desperate refugees.
Navigating through fierce battles, Theo risks everything to rescue Kee and her newborn amidst the hail of gunfire, where an awe-inspiring moment occurs—combatants on both sides pause, enchanted by the sight of a newborn. This brief ceasefire becomes their chance for escape, leading them to a fraught voyage toward freedom. In a poignant moment as they row away to safety, Theo reveals his own injuries to Kee, and as the ominous clouds of bombings gather overhead, she promises to name her child Dylan in remembrance of her fallen son. As Theo drifts into unconsciousness, Kee tenderly sings a lullaby, heralding an uncertain but hopeful future as the ship Tomorrow emerges from the fog.
