One day during the way home, Courtney and her sister has accident. Her sister died after that, since then Courtney is looking for the information after life.
9 years later, Courtney becomes doctor’s intern in ER. She and her friends are working on afterlife experiment during night.
One day she recruits Sophia and Jamie to help her test, she is looking for information after people died. She wants them to help her back after her heart stop for minute.
After died, Jaime scan her brain and record the result. She feels that she floating around to many place, minute later they try to revives her back but failed.
Sophia panics and call help from her friends, Courtney is dead for couple minutes. Ray help them get her back finally. Marlo shows up and later confusing what happen.
Courtney explains what she see to them, after check scan data they found the brain activity after the dead. After that Courtney starts to change, her brain and body are well improved.
Her friends notices the change on her, she is suddenly good with everything. They start to think it’s because her brain’s data is accessible again. They start to want the same experiment as her.
Onenight Courtney start to see something strange happen, Jamie is the next one who try the Flatliners. He is dead for minutes also after he is brought back. Before he backs he heard someone whisper at him.
After that Jaime also start to see strange thing, next night Marlo wants to be next Flatliners. Instead of see nice thing, she see her nightmare, they almost didn’t get her back.
Later that night Sophia shows up and tell them she also want it now, they agree to do it even it’s almost time that cleaning crew will show up.
After her flatliners she see her terrible past, then they see the cleaning crew show up so they have to hurry up and get her back before they spotted. They get her back safety before guards show up.
They go to party to celebrate, there Courtney notices someone like her sister. She following her to the parking and lost her. After that she starts to remember what happen to the accident again.
Jaime backs to his boat and heard the crying, he starts to see his baby and his ex. Courtney call him about what she saw, he rush to see her.
When Courtney goes back home, she see her sister again and she look angry at her. She try to escape but she is push back from the ladder and death.
Next day her friends get news about her death, they are all sorry and surprised. They think what happen to Courtney might happen to them. They try to cover about Flatliners by destroy all evidence about it.
But Jaime and Ray can’t find her phone, he asks Marlo down to the morgue to get it from her belonging. There she start to see strange thing that terrify her.
At night Jaime starts to hear crying from his radio, after he destroy the radio he hear woman voice. He saw his death ex, while he surprise he fell in water and stabbed by her.
He tells his friends what happen about his ex and to him, they think their guilt come after them and it’s going to kill them.
Sophia also did the wrong thing to her friend, she starts to see her friend too. She try to escape from her and end up in the elevator, it starts to move fast then she found herself back to present.
Jay found secret about Marlo, seem she changed to report to hide her mistake. He try to get her confess but she won’t.
Jaime and Sophia go to see Sophia’s friend and confess to her, her friend forgive her. They think it works, so he goes to see his ex to ask forgiveness. But he found that her son still alive.
Next day while Marlo driving, she is suffocated by someone from her seat back. They try to find her and help her, they found her at the basement. She killed herself again to be in Flatliners.
She try to apologize the one who she wrong but he attack her instead. Her friends try to revive her back but she won’t back. Ray won’t gives up, Marlo see Courtney inside.
She tells her to forgive herself, Ray success to get Marlo back. Jaime tells his friends about his family, while Marlo confess what she did.