One definition of complication is that it is

A series of difficulties forming the central action in a narrative.

Using this definition, I would say that the complication is the whole middle of the story.  This is the part where the lawyer is spending his 15 years in solitude.  During this part of the story, the lawyer is trying to keep himself sane.  He is doing that in a variety of ways -- through various kinds of books and music.  He is also, at times, drinking a lot.

In this part of the story, we are seeing what the lawyer will do to try to deal with his "imprisonment."