Mitchell Wells, a guilt-ridden brother, builds a time machine to go back in time and save his sister, Lindsay's, life. The story revolves around the Gateway, a powerful machine designed by Mitchell's sister Lindsay and built by Mitchell himself. The Gateway has the ability to bring a person back through time where they can interact with the past. Unfortunately, Lindsay was unable to finish the formula for the machine before her untimely death, and as a result the Gateway is malfunctioning. Mitchell can only return to the past for 148 seconds before he is brought back to the present and all his changes are reversed. In his last few minutes with his sister he must choose between fixing the formula or repairing his relationship with Lindsay.