A kid named Jake sits atop a radio tower, plotting a spiral of numbers across two notebook pages packed with rows of smaller, penciled numbers. He's 11 years old, and he's never spoken. But in voiceover, he tells us that the ratio is always the same: 1 to 1.618, over and over. Patterns are hidden in plain sight, but only some see how the pieces fit. As he speaks, we see shots of people around the world, including a British man named Simon in an airport, who doesn't notice that his cell phone, decorated with pink teddy bear stickers, fall from his bag.
Jake continues: An ancient Chinese myth says the gods have tied a red thread around our ankles and attached it to all the people whose lives we're destined to touch. It's all predetermined by mathematical probability, and it's Jake's job to keep track of those numbers and connect people.
Jake's dad, Martin Bohm, is a baggage handler at New York's JFK Airport. Once a highly paid reporter, he's held several less prestigious jobs since his stockbroker wife died on 9/11. He takes home lost cell phones because Jake likes them. Among his latest haul, Simon's teddy bear phone rings. Simon explains that people have been skipping it around the globe for two days, but he needs a photograph inside, of his daughter. Her birthday is tomorrow.
Martin's distracted when Jake's school calls. His son climbed a radio tower — for the third time in three weeks. Forgotten, Simon's phone trundles away atop someone's suitcase.
Martin, who's afraid of heights, entices Jake down with the phones and learns that, all three times, Jake tripped the alarm at exactly 3:18. At a gas station, Jake scribbles in his notebook behind a school bus from District 318. Inside, a man with "318" tattooed across his right fingers, whose name we later learn is Randy, selects lottery numbers: 87 1 9 20 31 11. Jake grabs the ticket, locks himself in the car to write down the numbers, then calmly returns it. Randy and Martin tussle briefly.
The teddy bear phone travels to Dublin, where a man records a video of his friend, aspiring singer/call center worker Kayla Graham. Then it goes to Tokyo in a businessman's luggage.
Randy sticks his lottery ticket to his apartment wall . . . alongside hundreds more with the same numbers.
Jake arranges a dozen phones in a spiral, winding outward from his notebook. Suddenly, they all ring — all showing the same number, Randy's lottery numbers.
Social worker Clea Hopkins arrives to assess Jake. She notes Martin's low-paying job and comments on his nice big loft. He testily explains it was his wife's. Her family's wealthy, but Martin made her put everything in a trust for Jake. He warns that Jake can't stand being touched, not even by him. Then he sees a headline about the mystery multi-million-dollar lottery winner — the same numbers from Jake's cell phones.
After hearing his winning numbers announced, Randy buys a train ticket home to Lynchburg, Virginia.
Skeptical, Clea says that autistic children are often good with numbers, but Martin never bought that label for Jake. Anyway, Jake will be evaluated for two weeks at a live-in facility, to determine if he should be institutionalized. Later, a distraught Martin visits his wife Sarah's grave and finds a Fire Department medallion, number 318.
A Web search leads Martin to the Teller Institute, a rundown home at 318 West Tesla Street. A man in a bathrobe explains that, on his own, Jake discovered the Fibonacci sequence, a mathematical ratio concerning patterns repeated in nature: a wave's curve, a shell's spiral, segments of a pineapple. Jake sees vast connections that amount to road maps, and it's Martin's job, his destiny, to follow them for Jake.
Martin tracks Jake's numbers to a Grand Central Station pay phone. He frantically grabs the man who's using it. It's Randy! They start fighting. As transit police cuff them, Martin despairs.
Back home, Martin plays a message: It's Randall Meade, formerly with Ladder Company 318. He found Martin's wife, Sarah, on the 87th floor of the North Tower, barely conscious and badly bleeding, and carried her down 31 flights of stairs but couldn't go any farther. He's played the same Lotto numbers every week: 9/11/2001, 87th floor, 31 flights. He wanted to make them come out right. As Randall says that he thinks Sarah would want him to give his winnings away, Martin hears himself say he really needs that phone.
Stunned, Martin sees a news report about Randall saving children from a burning bus. He was only there because he missed his train. Martin rushes to the care facility, where Clea says Jake's missing.
Now in Tokyo, Simon calls his service provider and gets Kayla . . . whose video is playing on the Jumbotron behind Simon, thanks to a prostitute whose friend posted everything from the teddy bear phone. Simon mentions he sells restaurant supplies and tells Kayla that the phone has photos of his daughter, who died a year ago today.
Suddenly, an amazed Simon watches those photos flashing across the Jumbotron.
Kayla finds the phone: It's on a bomb strapped to an Iraqi boy. He's doing this to get his family's bakery a new oven. Remembering Simon's job, Kayla says she can help. The boy stops the bomb.
As Clea and Martin find Jake at the tower, we see Kayla learning that her video has 1.6 million views, the Iraqi family getting an oven, and Randy taking a bus home.
Martin shakily climbs up, telling Jake the kids were saved — and he hears him now. Jake hugs his father, then grabs Martin's cell and dials. "This is gonna sound crazy," Martin tells the man who answers, "but I think we're supposed to find each other."