During the previous volume, the rookie detective Jan Suk not only discovers the corruption of some of his superiors in the Prague police, but they have been murdered by a mysterious person, without realising a blonde woman he met at a bar and has fallen for, named Anna Liebert. At the start of the volume, as Anna walks home to her apartment and as she steps into her bathroom, it is revealed that she is Johan, masquerading as his twin sister, who now goes by Nina Fortner. Once again, pretty boy Johan is up to no good.
As Suk dives deeper into the larger conspiracy involving the origins of 511 Kinderheim, putting his life in danger, Kenzo Tenma and the freelance journalist Grimmer join forces to uncover this epic mystery, whilst other characters such as Nina, Dieter and Inspector Lunge are thrown into the mix. Grimmer, in particular, sheds more light in this tragic backstory, which includes being a child subject in 511 Kinderheim, which left him emotionally cold, even during the loss of his child. For a man who smiles a lot, there is a darkness within him.
What seems to be the climax of Grimmer’s arc, it sets up “The Cruellest Thing” that Johan has ever done. It's not just the case of Johan committing serial murder, but how he psychologically manipulates his victims to their fate, including sending an orphaned boy named Milosh to a nearby red light district in a fruitless search to find his mother, and convinces him that he is not wanted. Leaving Milosh depressed and suicidal, Tenma and Grimmer manages to save him, leading to an unexpected intense emotional experience for both Grimmer and Milosh. This sequence alone shows the brilliance of Monster, in that how much darkness flows throughout, a shade of light can still shine. Also, I’m not crying, you’re crying.
During the final chapters, there are flashbacks of Hans Georg Schuwald’s brief romance with the woman who would bear his son, as he talks to Dr Reichwein in the present day. Through this constant discussion of the past, as well as the journey of multiple characters who are heading into the same direction, we are getting closer to the possible origins of the Liebert twins. Mystery does it continue as this volume ends on a huge cliffhanger, leading to troubling times for Dr Tenma, which is exciting to see what Naoki Urasawa has in store for us.