On a small island in the Indian Ocean, one of the planet’s largest land migrations takes place. Forty million crabs make their way through dense jungle to the rugged coast and, finally, to sea. But Christmas Island’s sublime beauty hides another, darker presence: The Australian government runs a high-security detention facility deep within the island’s jungles, where asylum-seekers wait indefinitely to hear whether they can continue on to Australia. Meanwhile, local islanders carry out “hungry ghost” rituals for the spirits of those who died on the island without receiving a proper burial. Gabrielle Brady’s hypnotic documentary focuses on Poh Lin—a trauma therapist who works with inmates of the detention center. Following Lin as she explores the island and speaks to her clients, Brady brings together the island’s violent past, Lin’s therapy sessions, and the relentless drive of the migrating crabs in a sharply beautiful, haunting meditation on how a place can reflect its own past and present.