OKAY SO Seungmin’s (top) friend realises that Jaeyoung (mc/bottom) IS the patient that the doctor is treating due to the side effects of the happy drug. then, it shows Jun who is seemingly abroad. Jun is the one that drugged Jaeyoung all those years ago and used to be in the same idol group as him. Jun is talking to his lady friend about going back to Korea and the friend asks him if he is going to bring the ‘dog’ back abroad with him, we can assume that the ‘dog’ is Jaeyoung! Jun then goes and kisses the brown haired man in the pool and spreads the happy drug onto his gums (?) we which paralyses brown haired man, causing him to drown. What Jun is holding at the end is the brown haired man’s police ID, so brown haired man was basically an undercover police officer who was likely investigating the happy drug trade! i hope this helped a little T-T

Sincerely asking can anyone EXPLAIN this chapter for me??