Mart arrives at Cal's door and pressures him to join the men in dealing with Johnny Reddy. Cal initially resists but ultimately agrees, recognizing his place in the community. Meanwhile, at the Reddy house, Trey returns to find her father gone, taken by Senan and Bobby. Sheila, eerily peaceful, sits eating toast and tells Trey she killed Rushborough herself. She lured him to the shed with the promise of fifteen thousand euros saved for Trey's college, and bludgeoned him with a hammer when he bent to retrieve a toolbox. She killed Rushborough rather than Johnny because she had married Johnny, and because she needed Cal to remain free to give Trey a future. Lena's offer to take in the children removed Sheila's last obstacle.

Trey realizes the shed is full of forensic evidence implicating her mother. She decides to destroy it. Sheila packs the younger children, Maeve, and Banjo into the car; Maeve only cooperates after Trey claims she's protecting their father from Nealon. Sheila drives them to Lena's. Trey stays behind, takes Brendan's watch, fetches a petrol can, and prepares to burn the shed.

Meanwhile, the men of Ardnakelty force Johnny to dig what looks like his own grave. Johnny pleads and bargains; Cal watches, uncertain whether the men intend to kill him. Cal receives Lena's text saying Sheila and the children are safe but Trey is still on the mountain. He looks up to see flames on the mountainside. Johnny insists on coming with Cal and they race up the road.

Trey lights a petrol-soaked rag and throws it into the shed, igniting an inferno that quickly spreads to the drought-dry spruce grove. Jumping from a wall, she twists her ankle badly. Using a tree branch as a crutch, she limps painfully down the mountain through smoke and falling embers. Cal and Johnny push through the flames and find her staggering out. They get her to the car.

Johnny kneels before Trey and offers a self-pitying speech about always feeling he was falling, urging her to take the chance Cal offers. He concocts a final story: he and Cal split up, and Johnny was lost in the fire. Cal hands him cash. Johnny throws his phone toward the flames, asks Trey to tell Sheila he's sorry, and runs off over the mountain as sirens approach.