“Game of Thrones” fans are inching closer to learning the truth about Jon Snow’s parents. The Lord Commander was brought back from the dead in episode 2, and now Sunday’s installment will shed some light on the Tower of Joy, a scene from George R.R. Martin’s books that sparked the popular R+L=J theory.

As previously reported, episode 3 is titled “Oathbreaker.” Last week HBO viewers got to catch up with Bran (Isaac Hempstead Wright), who has been training with the Three-Eyed Raven (Max von Sydow). It appears as if he’ll learn more about his past and family through another flashback. Promo videos for “Oathbreaker” reveal that Bran will get to watch a young Ned Stark battle at the Tower of Joy.

But what exactly is the Tower of Joy? And why is it so important to the story? In order to explain, we need to start with the Tourney at Harrenhal.

Game of Thrones The Three-Eyed Raven (Max von Sydow) will help Bran (Isaac Hempstead Wright) with another flashback in episode 3 of “Game of Thrones.” This time exposing the Tower of Joy. Photo: HBO

Rhaegar Targaryen, the brother of Daenerys, was the eldest son of Aerys II Targaryen and next in line for the throne. However, he didn’t have a good relationship with his father because Aerys believed that his son was trying to remove him from the Iron Throne. Aerys attended the tournament because it was believed that Rhaegar was plotting something. But the big turn of events was when Rhaegar defeated his opponents and took the winter rose crown and gifted it to Lyanna Stark, Ned’s sister. This wouldn’t have been a big deal except for the fact that Rhaegar was married to Princess Elia of Dorne, and Lyanna was engaged to Robert Baratheon.

Shortly after the events at the tourney at Harrenhal, Rhaegar allegedly kidnapped Lyanna, sparking Robert’s Rebellion. But the theory amongst fans is that Lyanna fell in love with Rhaegar and ran off to be with him.

The Lannister’s joined forces with Robert Baratheon and took part in the rebellion, with Jaime Lannister killing Aerys after he ordered King’s Landing to be burned to the ground. Meanwhile, Robert engaged in battle with Rhaegar at the crossing of the Trident. He slaughtered Rhaegar, and then sent the order for his men to kill Rhaegar’s wife and children.

That brings us to the Tower of Joy. In Martin’s “A Song of Ice and Fire” novels, the Tower of Joy is located in Dorne. Ned led a group of men there to free Lyanna, who Rhaegar was keeping guarded there by three of his men. It was a bloody battle that resulted in many deaths, but Ned was able to get to Lyanna. Unfortunately, he didn’t get there in time. He found her laying in bed in a pool of blood. Before she died she made Ned promise something to her. However, that promise was never revealed.

The people in the Seven Kingdoms know two different versions of Lyanna and Rhaegar’s story. Those that supported Robert believe that Rhaegar had kidnapped Lyanna and raped her. While Targaryen supporters believe that Rhaegar truly loved Lyanna.

Hopefully Bran’s flashback in episode 3 of “Game of Thrones” will shed more light and finally reveal the truth about Jon Snow’s (Kit Harington) parents.