Frisk, the not quite immortal goddess of Night and Darkness, has been kept in her home with her mother and twin brother most of her life. She's met most of the other gods, yeah, but there's a pair she's always wanted to see, but hasn't been allowed to.
She and her brother are finally allowed out of the house for a party. There, she meets one of those gods. Sans, the older of the two Gods of Death. They become fast friends, and he quickly learns of her secret.
A childish bet, some annoyed siblings, some spicy potato chips, and a mutual love for the stars await the unusual pair in a future of confusion, hiding and sacrifice.
What would you do if you fell in love with the one person who could kill you in an instant?