A luminous portrait of love in its many forms—yearning, obsession, addiction—and just how messy and destructive it can be

Robin is unreliable, unstable, and utterly devoted to his oldest friend Henry. So when Henry's beloved mother—the lauded novelist Marian Finch—dies unexpectedly, Robin is there to pick up the pieces. Henry comes into possession of a venerable antiquarian bookshop and there—for a time—they build a life, with their found family of sorts.

But grief can send us down unexpected paths. For Henry, it leads him to the theory of multiple universes and to Yolanda, a brilliant scientist who can help him understand it.

Robin and Yolanda have three things in common: they are in love with the same man, they despise each other, and they are oblivious to the fact that Henry is spiralling into a dangerous obsession that will irrevocably change them all.