Elena, 35, is a cynic about relationships. Jake, 26, is a romantic. They meet randomly and have what they both presume to be a one-night-stand. They meet again, and consumed by infatuation, they spend day and night together, missing work, and talking into the early hours. [Jake] seamlessly moves in with Elena and she reveals a secret: for fear of rejection she lied about her age. She's not 29, she's 32. [Jake] doesn't care and says she's gorgeous. A little later she's 33, or 34, or 35? He points out she has aged six years in four hours. She says he'll be 30 when she is 40, and he might want to break up with her, but he says he doesn't care.
Elena insists the age difference is a problem — her parents' divorce has given her a fundamental mistrust of relationships. She pushes Jake away, professing that she is ready to have children and he is too young — their relationship will not last. Jake's mum died when he was seven, and he was raised by a father devoted to his wife, who has not had another relationship since her death. Jake has inherited a certainty about love and commitment which Elena cannot resist. Jake tells Elena he wants nothing more than to make a family with her and he doesn't want to waste any time. They start to make love.
Six months later Elena isn't pregnant. A casual trip to the GP to check things is okay leads to tests at the hospital and a tense appointment during which Elena also reveals she had an abortion as a teenager. They are told that there is nothing wrong with either of them, but because they have been trying for over six months and Elena is over 35 years of age, they should put themselves on the list for an IVF date in another six months’ time. Elena has a horrible sense of foreboding. They have already embarked on a journey from which there is no turning back. Jake is optimistic. He is convinced that they will manage to conceive before the months are up. Elena is uplifted by Jake's optimism and buys into the idea that they will manage to have a baby naturally.
The months go by. Sex becomes strategically timed. It leads to nothing but disappointment and IVF starts to feel inevitable. Elena and Jake try to face it with optimism. They put it to the back of their minds that the odds of IVF resulting in a pregnancy are low. They embrace the injections and appointments and interventions. It is an opportunity to have a baby. It will be worth it. But it fails.
They both begin to privately doubt the possibility of ever having a family. They take out their disappointment on each other. Elena has a growing paranoia that Jake will leave her if she doesn't give him a child. A second round of IVF fails. An explosive argument leads to Elena telling Jake to leave. Jake tells Elena if he goes he will never come back.
After time apart, Elena attends her best friend's wedding and when she returns home that evening she gathers Jake's remaining belongings and texts him suggesting they meet so she can deliver them to him. They meet in a cafe and Elena breaks down. She is still profoundly in love with him and she tells him he was right when he said that they already were a family and that what they had together was too special to lose. Jake walks out abruptly leaving Elena in tears. He goes to stay with his dad and talks to him about Elena. He tells his dad that he doesn't know what to do, he and Elena had a perfect relationship just like his dad and mum did and he doesn't know how to get that back. His dad explains to Jake that perfection is just an illusion. He asks Jake if he still loves Elena and Jake nods. He then asks him what he will do if they never have children together; Jake covers his face with his hands. In the penultimate scene Jake sits alone, thoughtful.
In the final scene, Elena walks through the park on an autumnal afternoon. She eventually comes to Jake who stands waiting for her. They walk towards and embrace each other tenderly.
