"That Winter, The Wind Blows" Jo In Sung discovers the real reason why Song Hye Kyo went blind.

During the 12th episode of the SBS drama "That Winter, The Wind Blows" that aired March 20, featured Oh Young (Song Hye Kyo) undergoing various tests for her surgery and Oh Soo (Jo In Sung) getting constant updates from the surgeon.

The doctor tells Oh Soo that he figured out the reason why Oh Young went blind. He says, "It is not because of her brain tumor. It she received treatment for her condition, she wouldn't have been locked home all these years. If it was because of the tumor, her eyes wouldn't be so clear and beautiful."

However, the test results showed that her eyes were impossible to perform surgery on. The doctor added, "The patient was kept in captivity for too long."

Oh Soo is completely overcome with anger after hearing the doctor's words. He is about to hit Secretary Wang (Bae Jong Ok) but says, "I want to kill you with every last bit of energy I have but I'm going to control myself."

Oh Soo says, "Oh Young is not blind from the tumor but because of RP. If Oh Young's surgery goes wrong and she can never see... don't ever think about acting like you care about her in front of me ever again."

Oh Soo then chases the doctor who prevented treatment for Oh Young's eyes years back with his car. When the doctor keeps going, Oh Soo throws a glass bottle at the doctor's car and forces the car to stop. Oh Soo drags the doctor out and begins to beat him.