At the heart of the novel is Capote's question about himself. He writes much of his material of the two killers about Perry Smith while maintaining Perry's sensibilities. Capote archives the sordid details of Perry's childhood and family background; it is loathsome and painful--pure pathos in some respects. However, he then contrasts the portrayal of an irreparably broken young man with the carnival crowd seeking justice.
Capote makes far less of a case for Dick Hickock who was raised by two doting, questionably over-indulgent, parents who saw their son as a goldenboy with a favorable reputation in high school as an all-American athlete. His childhood and family background were fairly average with some exceptions. However, Capote makes no excuses for Dick's anti-social behaviors, amongst them being a pedophile.
Again, the question arises about the crowd and the accused. They were equally cold-blooded. The trial was rife with corruption. The jury, the judge, the attorneys, the venue, all acquaintances of the deceased. An old law that predated the colonies excised any mental health professionals from testifying on behalf of the accused. Capote notes that Smith is a writer, a gifted artist, an intellectual snob. These are the very same descriptors used by New York socialites to portray Capote himself.
As the other responses detail, this is a book about two murderers and Capote's relation to them. This novel was written in a pioneering style for the time, and received much attention. The start of the creative non-fiction novel begins here with Capote, but it must also be understood that Capote took a great deal of liberty with the facts when writing this novel.
The events of the novel follow in the basic murder-inprisonment-trial-and-death sequence, with Capote documenting these events along the way.
In addition to the other response--
Capote's book started a new genre called the non-fiction novel. He claimed that the book was 100% true, though he never took notes during the interviews. He claimed to have a 96% recall. However, after reading the book, which entwines the Clutter family's last day, the murders' premeditation and planning, and then continues on to the investigation, arrest and eventually trials of Dick and Perry, it's obvious Capote would have had to make up some of the scenes and details.
Another interesting aspect of his book is his treatment of the criminals. It was rumors that Capote was romantically involved with Perry, but Capote poses an interesting questions when delving into the background of Perry--how much can be blamed on background? It's the nature vs. nurture discussion. Capote write with such deft that the reader comes away almost feeling sorry for Perry.
It's an interesting book to start a discussion about what causes violence and crimes and who is ultimately responsible. It also brings up great questions about the criminal justice system and the punishments, including the death penalty.
Hope this helped!
_In Cold Blood_ is the story of the murder of a family in a Kansas farmhouse by two drifters written by Truman Capote. The story reads like a novel, yet it is really non-fiction. Capote did a lot of research and became somewhat personally involved with the murders. The film _Capote_ details his experiences.