Real underworld novels usually involved violence, drugs, sex, crime, politics, society, and other elements. They also often had complicated interpersonal relationships and plot developments. These novels might describe the details of criminal activities, including robbery, murder, kidnapping, extortion, etc. They might also describe the growth and changes of the protagonist in the criminal world. Some true underworld novels may also involve political and social issues in an attempt to reveal and solve these problems. It should be noted that real underworld novels are different from the usual entertainment novels. They may contain some negative elements such as violence, crime, abuse, etc. and may have a negative impact on the readers. Therefore, if you're looking for an entertainment novel, I suggest you choose another type of book.