A marine biology student, Siobhán, a solitary and intensely focused researcher played by Hermione Corfield, joins the crew of a rickety fishing trawler for a routine voyage off the coast of Ireland. The vessel, captained by the weary Gerard (played by Dougray Scott) and his pragmatic wife Freya (played by Connie Nielsen), is a tight-knit, working-class world that clashes with Siobhán's academic detachment. Their journey takes a terrifying turn when they become entangled in an enormous, bioluminescent creature that cripples the boat. Stranded and isolated at sea, the crew discovers they have been exposed to a parasitic, otherworldly organism that begins to infect them one by one. Directed by Neasa Hardiman, this taut The Thing-esque thriller masterfully blends claustrophobic horror with the stark beauty of the ocean, forcing Siobhán to use her scientific knowledge against an escalating biological threat. As paranoia and desperation mount, the crew must confront an impossible choice between quarantine and survival, all while a luminous, alien presence lurks just beneath the waves.