The relationship between Heather Katchadourian and Julie Howe is complicated. Over the past two decades, they've been just about everything to each other: boarding school roommates, best friends, lovers, rivals, even co-parents-both together and estranged. Will they find their way back to each other, or have they inflicted too much damage along the way? Reminiscent of the work of Meg Wolitzer, and narrated by Heather, Julie, their lifelong friends, partners, and children, The Light Source is a prismatic portrayal of what everlasting modern love truly looks like and reminds us that what's meant-to-be becomes harder to define with age.