Charlotte and Simon are ready to move on with their lives after dismantling the black-ops agency known as Quantym. But Charlotte begins suffering from nightmares and disturbing visions, and she fears events on the Periphery—her parallel life—are impacting her via the bleed-through effect. In a dual timeline between the main reality and the Periphery, Charlotte and Simon must confront the blurred lines between strength and weakness, love and loyalty, and their past and future. As they struggle to regain control over their lives, a catastrophic secret is revealed, a vengeful lover on a quest for power closes in, and Charlotte must figure out a way forward...even when the past refuses to let go.