When Jem was little she could see numbers when she made eye contact with others. She never knew what they meant until she found her mother dead. The day of her mothers death was the same as the numbers she saw when she looked into her mothers eyes.
Jem and Spider were in line waiting to go on the Ferris Wheel. Jem noticed that when she made eye contact with the people there they all had the same date, and that date was that day. She knew something bad was going to happen, so she told Spider that they need to leave.
After they saw what happened and Spider learned about Jem they went to Spider's house. They found out that they were suspects from the terrorist attack because they were seen running away from the scene. They have got in trouble with the police they choose to run. Spider's grandma helps them pack, they take a car and they were gone.
Jem and Spider were getting chased by the police, so they went to find a hiding spot in the bushes. When Spider thought it was clear and no police were out anymore, he went out to go get a car so they could leave town. When Spider didn't come back Jem didn't know what happened until the police came over by the bushes and looked around. Jem didn't get caught but at that moment she knew what happened with Spider.
The police find Jem and she hides in a church because they can't do anything to her while shes in there. So she tells them that she won't talk unless she gets Spider. They make an agreement and she talks, she tells them everything. About the numbers, the terrorist attack. Word spreads fast about her seeing dates and people stared filling up the church wanting to know their dates and she was overwhelmed.
In the end Spider ends up dying and Jem saw it happen. After that she broke down and stopped talking so she went somewhere to help her. Soon After she found out she was pregnant with Spider's baby. She gave birth to a boy, Adam, and after the birth she stopped seeing numbers. Than one day Adam said the numbers that he saw when he looked into Jems eyes.