Future Lost — Elizabeth Briggs

It's been a year since Elena and Adam were first recruited by Aether Corporation and six months since they destroyed the accelerator. Now Elena's in college and Adam is working on making his cure for cancer safe for the public. But Adam will be anything to figure out his cure, and when he goes missing, Elena realizes that he's done the unthinkable: he went to Aether for help.

Using Aether's new accelerator, Adam traveled into the future to find the fix for his cure, but he didn't come back when he was supposed to. Elena decides to risk future shock and time travels once more, but this future is nothing like they've seen before. Someone has weaponized Adam's cure and created a dangerous pandemic, leading to the destruction of civilization. If Elena can't find Adam and stop this, everyone is at risk. And someone will do anything to keep her from succeeding.