The Map of Longing by Alice Kellen

Her late sister's game begins with one unmistakable clue. 

But who is Will Tucker?

Grace Peterson was born for a purpose: to save her older sister Lucy. Her blood cells were to cure her sister's leukemia, and for awhile, they did. But when Lucy dies, Greta's reason for existing vanishes. She's always felt invisible anyway, burying herself in her writing. She never left Nebraska, and now there's nowhere to go. 

Then one day, Greta finds a box Lucy left behind―a game so cunning, so personal, it feels like a last whisper. Lucy's map sends Grace on a quest to find a man she's never heard of, Will Tucker. The rules are simple: follow the clues. But the journey? That will turn into something far more.

As Greta and Will navigate Lucy's challenges, they begin to unearth not just secrets―but the raw edges of themselves: grief and guilt, longing and redemption, dreams buried and hope reclaimed. Lucy's map was meant to guide Greta and Will to the real discovery that they might find in each other.