"Game of Thrones'" source material "The Winds of Winter" serves as fans basis in predicting the major story arcs in the HBO series. However, it has been revealed that the final book has not yet been completed.

According to Christian Daily, HBO's "Game of Thrones" had caught up with the last novel as the series' season 6, which is set to air on the network soon. However, "Winds of Winter" was yet to be found, as per the publication.

Since "Winds of Winter" has not yet been finished, various speculations on the "Game of Thrones" season 6 plot have emerged. According to iDigital Times, the book might see the fate or origin story of fan favorite character Jon Snow, which is said as the most notable spoiler among, others.

Jon Snow's death at the conclusion of "Game of Thrones" season 5 has been "plastered" on the series marketing for the next season and supporting rumors claim that the character could still be alive. As per the publication, the possibility of bringing Snow to life in the series is not far from happening if he comes back to life in "Winds of Winter."

Aside from Snow's fate, "Winds of Winter" may dig deeper the mysteries behind Bran Stark's visions. "Game of Thrones" fans saw Stark meet the three-eyed cow/raven at the conclusion of season 4 and in "A Dance With Dragons." Perhaps, the book, along with season 6 would showcase more profound details attached to such visions.

Authored by George R.R. Martin, "Winds of Winter" stands as the basic for "Game of Thrones." In his interview with IGN, Martin revealed that the book involved a dead character, one of who was dead in the show but undead in the books. He added that the show could not do it, since they had killed a character that had not killed.

"Winds of Winter" is assumed to be released in late 2016 or early 2017. Meanwhile, "Game of Thrones" season 6 is set to return on Apr. 26 on HBO.