When Laurel Everett finds a ring in her longtime boyfriend Ollie's sock drawer, she should be thrilled . . . so why is she left wondering "what if?" Specifically, what if she'd taken up her work crush, Drew, on his offer of a date just after she and Ollie got together? Thanks to her job at tech giant Pixel, she might have a way to answer that question through the AltR project, which promises users a glimpse of alternate realities. Or it will, once the quantum computers it relies on get more powerful.

When the program actually works and Laurel wakes up five years into her life with Drew, she's fascinated . . . then increasingly horrified as she continues to slip between that world and her "real" life seemingly at random. As she moves back and forth between the two worlds, Laurel realizes choosing the right life might not be as simple as deciding between two men and the different visions of happiness they offer. And if she doesn't find a way to untangle herself from the quantum mess she's unleashed, she might wind up stuck in the wrong life, or worse, deleted entirely like a faulty line of code. . . .