Many spoilers following. 

I took a brief foray into trauma studies when I was exploring ideas for my dissertation and I came across the quote, paraphrased here, that trauma is that which we cannot speak. And I feel like this book speaks very well to that idea. The book centers around these folk tales that are various preserved in different languages, in various forms, that are being destroyed, lost, redacted, erased, etc. The "folklorn" of the title captures this ephemerality of these stories folktales + forlorn, a familial, heritable illness (according to Elsa) encapsulating the ways that specifically the women of this family are trapped within a history that they can never know as women are erased, sacrificed, and killed. Oskar--a Korean adoptee to Sweden who has his PhD in studying Old Nordic languages and myths but teaches about Korean fables and poetry to be more "marketable"--emphasizes the inherency and prosthesis of language. He says, "I was adrift between languages, losing one while barely gaining another. I couldn't tame or give voice to my mad, wild thoughts. Couldn't explain or even understand how I was feeling. Felt like I was losing my mind. Not until I acquired a new language could I make sense of my own thoughts" (163-4). Language and stories are touchstones in this text both anchoring the characters to the "real" world, it's "real" problems, and to each other, but also setting them adrift, a linguistic diaspora. 

Ghosts and Ghost Particles and Ghosts of Ghost Particles
Elsa's career as a physicist starts as a mixture of two stereotypes: the "model minority" Asian child who is "naturally" good at math and science and the person who dedicates themselves to the sciences because they only believe "what they can see." Elsa explicitly embraces experimental physics specifically because it demonstrates things. But then she is working with neutrinos--a particle that cannot be observed, only its effects can be observed. And then declares her interest in working in the "ghost of the ghost particle," something even further removed from observable reality. In her very efforts to escape from the hauntings of her mother and her mother's ghosts, she embraces her own kind of ghost. She eventually is able to unit these two "opposing" forces together, to give greater clarity both to the stories and to the physics. Ghosts of all kinds are made slightly more and slightly less material.

Ghosts of any kind are always an interesting figure in a text. Elsa's friend/sister is variously a delusion, a ghost, some quasi-divine spirit, and something else undefined. Any time a character is being haunted--or a text is being haunted--there is always something else under and around the text that is structuring and de-structuring the text. Many authors cannot effectively balance the un/reality of a ghost, but Hur does an excellent job in always shifting the narratorial ground and keeping the text haunted. The reader is never let in on the truth to sit in judgement of Elsa. The moment that the "truth" of the matter is revealed, the narrative shifts slightly and everything is thrown into question yet again.

"never go skinny-dipping in lakes, never trust pirates or monks, beware of sea turtles"
I would be remiss to not mention the central element of the folktales that are included in the text: the ways women are represented within them. In comparing notes with Oskar, Elsa realizes that the versions of the tales her mother told and re-told are not the "traditional" versions of the stories, but expose more forcefully the way that women sacrifice for men's glorification and betterment. Part of what Elsa is doing throughout this text is a form of reclamation. In her final letter to her brother, she notes that he and she are the final predicted member's in their clan's naming poem. Now her brother has to decide if she and he are going to restart the naming conventions back at the beginning of the poem or if they are going to write their own poem. She encourages him to write his own poem--a tale that he (and she) will tell differently.

In the final moments of the book, Elsa's friend/sister tells her that everything will be repeated again, there is no escape. There are variations, but not enough to make any difference. But Elsa has learned something new, has in fact changed the story. And in this version of the story Elsa can set her sister--neither alive nor dead--free.