It started when Yeri decided to challenge her unnie to a bet, challenging her to face a zip-line adventure, one that especially runs across an expanse of water (just to deter Irene from the idea even more, since she wanted to laugh over Irene being a wuss when she flat-out refuses). Joy was also there shaking her head with laughter because she knew it would be a dream if Irene ever did agree. But gaped and her laughter stopped when all of a sudden, Irene actually stands up and slams her hands on the coffee table and says 'Of course I can do it! Who do you think I am?' And Yeri finding it amusing and taking the chance to follow up on Irene's weirdly braven attidude, drags them off to a nearby zip-lining location after making a couple of quick calls.

Joy isn't too convinced this was a good idea but her curiousity wills her to see how this would actually go, plus she would still support Irene. She knows that she wouldn't be able to stop her unnie even after she's made a decision as unexpected as this.

Joy couldn't imagine her unnie to ever agree. They both didn't expect Irene to agree at all. But even more, they didn't expect to see their unnie falling into the very same lakewater they had commented beforehand as a supposed 'water blackhole' which they merely cackled at in silly attempt in humouring themselves. But when Irene hears them question halfway up the tower, the two asking between themselves 'How deep is this lake though...' they immediately try to shrug it off after feeling bad for causing worry evidently haze over their unnie's eyes, 'Don't worry unnie, you wouldn't need to know that!'

But as if trolled by Irony, their unnie's rope snapped and they couldn't believe their eyes as they helplessly watched Irene drop, her body swallowed into the unknown depths of the man-made lake. Whilst their mouthes lay agape, their unnie's body invaded the body of water. Like a needle in a haystack.