Castle and Beckett investigate the murder of Gordon Burns, a body found in a pizza oven. Initially, it looks as though the pizza wars have gotten worse, but the body is a result of Burns getting too close to a drug dealer.
Burns was working a puff piece about the pizza wars when he discovered the heroin dealings taking place under the control of a mythical Cavalo. The detectives track down leads and find links to a supposedly deceased drug dealer Harley and a former girlfriend of Burns, Monica.
Beckett & Co. discover that Monica is the one behind the scenes, moving heroin through apartment complexes and Terrific Authentic Nick's pizza shop. After T.A. Nick refused to allow "Cavalo" to use his oven for the body, Burns ended up in oven of Authentic Nick's. Cavalo/Monica had gotten rid of Burns after he had gotten too close to figuring out the story.