Finch gives Reese another social security number from the machine -- another chance to stop something terrible from happening. But there's something strange about this number. It belongs to Theresa Whitaker -- a teenage girl who was murdered two years ago. Finch claims his machine is never wrong. So why is it pointing them toward someone that it's too late to save? What does the machine know that they don't? With Detective Carter still hunting them down, Reese and Finch begin to find out what really happened to Theresa -- and discover that they might still have a chance to be there in time.