Everyone is basically suffocating in the dining room. The windows won't open, the adults are forced to drink wine instead of the water they're craving, and nobody is particularly eager to eat a roast.
Needless to say, conversation is pretty slow. It isn't helped along by Cecilia and Robbie either, both of whom are lost in their own thoughts about the scene that just took place in the library.
Paul Marshall breaks the silence after three minutes (super awkward) by checking in with Robbie about tennis plans for the following day. When he speaks, Robbie notices a long scratch on his face.
More small talk follows, during which Briony snaps at Robbie and everyone discusses the heat. This is one seriously boring dinner party.
Robbie daydreams about Cecilia, imagining that he will be with her again soon and recalling the agony he felt after Briony ran away with his letter.
We are suddenly transported back to right before dinner. Robbie makes himself come into the house to find Cecilia and when she comes to the door he tells her he made a mistake with the letter.
Cecilia tells him Briony read it. He feels miserable and apologizes.
But all is not lost for Robbie. Cecilia leads him into the library, across the room and into a dark corner as he apologizes for his words.
They make love against the bookshelves and profess their love for each other. After so much build up, the whole thing is pretty frantic and romantic.
And then Briony comes in. Way to ruin it, Briony.
We are suddenly back at the dinner table where dessert has been served and the twins are whispering between themselves.
Forbidden from telling secrets at dinner, the twins ask to be excused. Briony realizes they are wearing her socks and protests. Cecilia snaps at her and Briony, who just wants to protect Cecilia, feels betrayed.
She points out Lola's injuries. Marshall says he saw the twins attack her—that he actually had to break the whole scene up—and Emily examines Lola more closely. When she does, she realizes that her wrists aren't merely burned, but that Lola is bruised halfway up her arms.
When Emily asks Lola how the twins managed to do so much damage, Lola says she has no idea.
Marshall tells her it's okay if she cries, and Emily pulls her in close.
For his part, Robbie finds himself wondering why Marshall hadn't mentioned the fight earlier considering his role in breaking it up and how badly hurt Lola was.
Amongst all of this commotion, Briony finds a letter left behind at the table by the twins.
It turns out that they haven't just left the dinner table, but the house. The letter they've left explains that they've decided to run away back home.
Lola panics and runs out after them.
Everyone else organizes into search parties. Leon grabs Cecilia, and Robbie decides if he can't be with his true love he'll search alone.