The Untamed Episode 6

At night, the trio drinks wine together but are discovered by Lan WangJi. To prevent Lan WangJi from complaining, Wei WuXian casts a talisman spell on him to get him to drink as the other two escape. However, one cup knocks him out cold so Wei WuXian lays him on the bed. When Wei WuXian then tells him that his headband is slanted, Lan WangJi panics and fails to straighten it, but also prevents Wei WuXian from helping as no outsiders should touch such a sacred item. The next day, the trio and Lan WangJi are punished. After Lan XiChen's recommendation to heal the injuries in the Cold Spring, Wei WuXian joins Lan WangJi. Suddenly, the two are pulled into the water and emerged in an icy cold cave. The guqin resting on the platform sends waves of attack at Wei WuXian as he is not of the Lan Sect, so he urges Lan WangJi to borrow his headband's spiritual power. The latter obliges and ties it on both their wrists. Lan WangJi then plays Inquiry on the guqin, ultimately causing Lan Yi to materialize. The two then learns of her story and the Stygian Iron. While outside, everyone is looking for them. (Source: Wikipedia)