In 1951, Nancy Bradley (Essie Davis) is giving a talk on dunlin birds and their murmurations, the swarming behaviour they make that can be beautiful but also mysterious. Her husband Edgar (Andrew Lincoln) also studies with her. The two thank their benefactors for giving them a video camera and reveal they will be traveling to an isolated island to use their new camera to study the dunlins there.
On the island the couple are placed in a beautiful old house. Edgar tries to get Nancy to dance with him and she does at first but then she pushes him away. Later Nancy thinks she sees a figure pass their bedroom door. The two record the birds some more and the next night Nancy hears a series of loud thumps in the house which lead her to the attic. There she finds the unusual sight of the Dunlins roosting in the attic of the house. While recording in the attic by herself while Edgar videos them outside Nancy hears someone whistling in the house. Later listening to the recording she hears static on the tape when the whistling occurred and then she hears a child's voice saying "I'm so cold." Although she hears the voice on the tape Edgar does not hear it.
Nancy and Edgar learn the last inhabitants of the house were a man, his wife and their son, many of their belongings are still in the house including photographs. Edgar finds an embroidery of the blonde woman which depicts her standing surrounded by dunlin birds. Nancy and Edgar's life continues to show strain as he wants to make love and she does not and she is uncomfortable when he is affectionate. Hearing a child crying Nancy finds letters scattered on the floor and learns the blonde woman's name was Claudette and the father of her child got her pregnant but was already married. Getting into another argument with Edgar Nancy is alone in the attic when she hears the child crying but this time also sees him dripping water and his face is bloated. A bird flies into the house and startles her and Edgar and in a panic the bird flies into a window and breaks it's neck. While in the bathtub that night Nancy hears a groaning woman and then the door flies open and Claudette comes in screaming at her "what did you do?"
During a fight over these visions, Edgar expresses frustration over Nancy never crying following the death of their daughter Ava. Despondent, he leaves for his research site the next morning. Alone, Nancy is chased by Claudette's screaming ghost and hears her son crying that his mother is angry with him. Comforting him, Nancy encourages him to run into the light. He does and disappears. Nancy witnesses Claudette kill herself, realizing that her angry screams were in anguish over drowning her son. Claudette's spirit is carried by an enormous bird murmuration, which envelops Nancy, allowing her to finally cry and confront her grief. Nancy calls Edgar over their two-way radio to say she loves him and she is finally ready to talk about Ava.
Tropes
- The '50s: The story takes place in 1951.
- Ghostly Wail: At first the hauntings are the forms of poltergeist and then as they get stronger Nancy hears the ghostly wails of Claudette before the ghosts can manifest as visible spectres.
- Go Mad from the Isolation: In life, Claudette was placed on the island by her family after becoming pregnant because it was isolated far away from civilization, and spent the following years there waiting for her lover to come back from the war. When he abandoned her instead, his betrayal and the isolation of the island eventually broke Claudette's sanity, causing her to drown her young son in the bathtub. When she realised what she had done, she committed suicide out of grief.
- Haunted House: The house has a lot of the tropes of a haunted house. The caretaker tries to deny it but then later admits that other people have also been haunted like Nancy is being.
- Haunted House Historian: The house's caretaker Mr. Grieves is well aware of the island's tragic history, though he claims to not believe in ghosts and becomes irate when Nancy presses him for information, brushing off her concerns as nonsense.
- Madness Mantra: Claudette screaming "what did you do?" at Nancy turns out to be Claudette's own mantra to herself after she killed her son.
- My God, What Have I Done?: It turns out the isolation of the island and abandonment by her lover caused Claudette to go insane and murder her young son. However, in a moment of clarity she became horrified by her own actions and committed suicide not long after.
- Psychopomp: The dunlins seem to take Claudette form when she jumps from the attic, they also help Nancy come to grips with her daughter's death.
- Unable to Cry: One of the issues of contention between Edgar and Nancy is that she has not cried for a year since their daughter's death. Nancy admits she feels sad but can't cry. At the end of the episode after facing the ghosts Nancy is finally able to cry and let out her grief.
- Would Hurt a Child: Claudette is placed on the island by her family, but after her lover leaves her and the isolation of the island gets to her.. she drowns her son.
