NOTE: This spoiler was submitted by Dan T
Sarah (Olivia Wilde), and Phil (Luke Wilson) are a young married couple in the New York City area. They take their young son of about 10 years old inside to a convenience store bathroom. Phil goes to get a juice from the freezer a few feet away. Mere seconds go by and he goes to talk to his son through the bathroom door, but there is no answer. Nor to his yelling through the door to his son. The gas clerk unlocks the door, and we see that the small bathroom inside the station, actually has no back wall, beyond the stalls. It simply opens to the garage where cars are repaired, and then the parking lot. The parents are quite surprised at this, as the small closed bath room inside the store, actually opens to the garage and outside. The pair frantically searches for their son around the station.
One year later, the couple is at a party and we can see they are not coping well with the loss of their son, who is still missing. Phil says Sarah is on lithium for mood stability, and we see her laughing hysterically while looking forlorn. Next we meet Giovanni Ribisi as Tim, Phil's brother, who is 'self-medicating' and living on their couch. He has odd ideas about life and talks a lot, and is a misfit type, compared to the clean cut couple. He is scolded by Sarah for never recalling their son's birthday. Later Tim tells Phil that Sarah can work things out on her own and does not need help.
The bulk of the film then alternates between the separate day to day activities of Sarah, versus Phil, who both deal with their child's loss poorly, and alone. They don't seem to help each other or talk about it much. We see Sarah is a teacher of middle schoolers. She is disconnected from her students, not showing much emotion. She notices a younger kid, Ty Simpkins as Adam, who is throwing a tantrum on the floor while another teacher scolds him for stealing books from the library again. Adam keeps talking about elephants, and we can see he is mentally challenged in some way. Later scenes show him being picked on in gym class. Yet Sarah says little to him and blankly watches him. On several nights, she seems to wander NYC in what looks like Union Square, simply looking at young boys. It is unclear if she is looking for her son, or has bad intent or any intent at all. Finally, she starts to talk to Adam more and more, and learns his parents are uncaring in his view of things. He seems to have autism or similar.
Phil meanwhile, we learn is actually a uniformed NYC police officer. He appears to aimlessly look at photos of his son on his work computer. At night, we see him attend a coping group. He befriends John Leguizamo as Pete, who's child was killed by a drunk driver, prompting vengeance fantasies from John if he ever found the man again. Phil says little, though. He gets called to a disturbance of a young couple fighting in their apartment. The woman pushes and hits her boyfriend, who says she sleeps with all their friends. She then makes a pass at Phil. Phil says little in response and does not seem to be interested or doing much police work. Later he goes to the convenience store where his son was taken, appears drunk or high. We see his friends avoid him at a bar. Phil goes to a roadside grave marker of sorts for his son, and kicks it over. He is increasingly drunk. He meets Pete and gives him the address of the killer of Pete's daughter seemingly from the police files. Pete is angry and asks what kind of friend would do this. Phil says it is what Pete said he wanted.
A detective meets the couple and has a lead. A man in a van was in the area at the time of the abduction, and child porn was found in his possession. They now have a suspect.
Meanwhile, Sarah appears to be regressing to a childish state. She dresses in a hoodie like her students, and listens to death metal she confiscated from one of them. We see her in a bathroom engaging in 'cutting' with a razor, making cuts into her skin. Sarah begins following Adam's mom, who appears to turn a trick in a gas station bathroom. She has no cash and Sarah has to buy her beer for her at the store. She does not say she is Adam's teacher. It is then implied Sarah is fired or suspended. She meets up with Tim and they smoke crack. Tim begins crying when he sees the cutting marks on her skin. This seems to be because Tim previously told Phil that Sarah can work things out on her own. Tim now sees that she clearly is falling apart.
Sarah next stalks Adam's dad to a bar. He recognizes her as Adam's teacher and is openly contemptuous of his son's disability, who was adopted. Sarah comes on to him and they have vigorous, emotionless sex in his apartment. Sarah takes her keys and picks up Adam at school, claiming his dad sent her, whereas it is unclear what Adam's dad knows about this. Now we clearly see she is abducting Adam. They drive to a burger place, and Sarah is nervous that a cop is there. Adam keeps rambling about elephants and other things obliviously. The detective meanwhile has called Phil to identify a shirt in an evidence bag, taken from the suspect with the van. Phil can barely look at the shirt, and it is strongly implied this means their son was murdered by the suspect.
Sarah is driving Adam to the airport she tells him, ignoring various calls and texts from concerned parties. She does answer Phil at last. She stops the car, then gets out and sobs uncontrollably at the news she hears, impliedly about her son's death. She gets back in but can barely drive. Adam is disconnected to most of this, rambling unrelatedly. He is suddenly very excited at something he sees and demands they pull over.
We see a lone elephant behind a large enclosure near the road, with some circus tents in the distance. Sarah and Adam cross the fence and walk up to the elephant, both oddly in awe of the gentle animal. Sarah looks directly in the elephant's eyes, touches its forehead. Sarah's face expresses wonder and amazement at the elephant as the screen goes black.