First, attention focuses on the real identity of ŌĆ£Big Mouse.ŌĆØ Who is this guy who rescues Park Chang Ho (Lee Jong Suk) at every moment of crisis? And why is he helping him? As Jerry (Kwak Dong Yeon), who was a strong candidate for Big Mouse, turned out to be nothing more than a helper, the search for Big Mouse returned to the starting point. Nevertheless, the speculations continue. ThereŌĆÖs a possibility that Park Chang Ho, whoŌĆÖs pretending to be Big Mouse, might actually be deceiving everyone. Or maybe someone playing a small role in the story, like Chang HoŌĆÖs friend Kim Soon Tae (Oh Eui Shik), might be holding the key to a twist. Still, the mayor of Gucheon (Kim Ju Hun), the warden who doesnŌĆÖt hide his dark ambition (Jung Jae Sung), Noh Park (Yang Hyung Wook) who shares the same room as Chang Ho are all suspicious. Besides, there might also be a chance that Big Mouse is not an individual. In the flashback scene, it was revealed that Park Chang Ho was from an orphanage, and we canŌĆÖt ignore the possibility that Big Mouse is an organization moving systematically in a shadow. Moreover, the unpublished thesis of Professor Seo Jae Yong (Park Hoon), the cause of the murder at Gucheon Hospital, has emerged as a major point of the series; the V.I.Ps even went to killing to stop it from getting published. Additionally, Han Jae Ho (Lee Yoo Joon), one of the V.I.Ps, showed extreme fear toward the thesis, saying, ŌĆ£The moment I open my mouth, IŌĆÖll be in hell even if IŌĆÖm alive.ŌĆØ Go Mi Ho (YoonA) found out that the thesis is now in the hands of Jang Hye Jin (Hong Ji Hee) after a persistent pursuit and persuaded her to hand it over to Gong Ji Hoon (Yang Kyung Won) for a deal. What exactly is the thesis about and what kind of a ripple effect will it have? Lastly, another key point is the Gucheon Hospital and Gucheon Prison, which seem like two separate institutions but clearly have some dirty connections. As Go Mi Ho has seen, there are a couple of suspicious circumstances in Gucheon Hospital. And the ŌĆ£closedŌĆØ tendency of the hospital starts with Hyun Joo Hee (Ok Ja Yeon), raising curiosity. Here, strange things were spotted at Gucheon Prison, which seemed to have no connection with the hospital other than volunteer work. While something fishy was witnessed as volunteers from the hospital collected blood in the name of physical examination, a prisoner suddenly vomited blood and collapsed. With this, you know that the two institutions have secret connections. Source (1)