Marlowe Evans is excited about attending a meeting of the secret Anglesey Philosophical Society at the Harlech Inn. At the meeting the conversation takes on what appears to Marlowe to be an unrelated undercurrent about whether present day justice is sufficient or whether others must step in and provide real justice in some cases. The hostess bursts into the private meeting room and through her tears manages to choke out that there has been some sort of animal incident at the spectacular, privately-held Duffield estate and that the police and the Greater Philadelphia Animal Shelter agents are there.
At Duffield Marlowe and her best friend Ashanti Ba see the aftermath of a dog fight. Marlowe speaks with a policeman who says he thinks other people at the scene are FBI. Marlowe, outraged and deeply saddened by what she's seen and learned, determines to discover clues to identify the person who organized the fight.
The next morning Marlowe gives a short, humorous investment seminar to three affluent ladies. The owner of the Duffield mansion walks into the seminar interrupting the meeting. From something the owner says, Marlowe realizes people had been scoping the site before the fight to make sure the property would work. That afternoon, at her new client Judge Gwyn Llewellyn's historic mansion, Snowdon, Marlowe is surprised when Gwyn asks unsettling questions about Marlowe's father figure, Nick. On the heels of those questions, she listens as Gwyn breaks down in agony relating what happened to her dog Raspberry which three months ago had been ripped apart in a fight at a barn in the nearby city of Lancaster. Overwhelmed by what she's just heard and what she'd seen at Duffield, Marlowe sits by herself sobbing in a garden gazebo. She feels powerless to deal with what occurred at Duffield and now Gwyn's dog. She has an epiphany. Whatever it takes, she will stop at nothing to somehow find the perpetrator and stop the madness.
Later that day Adam Mansfield, an Anglesey member, strongly requests she come to a second meeting to finish the prior meeting topic. He intimates the question is whether an individual is morally obligated to right a wrong if the authorities do not, will not or cannot. The following Saturday Marlowe goes to a magnificent party at Nick's country estate, Rocking Horse Downs, and gets more clues on who the perpetrator might be. Tuesday Adam calls Marlowe at her office and tells her to come outside to his car. Adam tells her they are going to meet Nick at ten o'clock on a dirt road to ask him about any involvement he has with the animal fighting that took place an hour and a half away in Lancaster. He says they need to hurry because the FBI will be there at eleven and they need to be gone. Marlowe protests that Nick would never be involved with the Lancaster incident. Adam pulls over and shows her a photo on his phone of Nick standing in the Lancaster barn. He gives her a gun just in case she needs to protect herself.
Nick and two men are waiting for them at the end of the road. Adam questions Nick. Ashanti comes running out of the woods saying Nick kidnapped her and tied her up in a spring house in the woods and she just broke free. Pressed first by Adam and then by Marlowe, Nick admits he ran the fights not only at Lancaster but also at Duffield and other locations. He pleads to Marlowe that he needs the betting money because he is being pressured by a Mexican cartel, and they have already shot his daughter Julie because he was not paying them fast enough. Marlowe is infuriated by the horror that Nick has unleashed on the animals. She knows because of his childhood he will continue animal fights to make money. As Nick is reaching in his jacket for what Marlowe suspects is a gun, she steels herself, squares her shoulders and declares, "I kill you in Raspberry's name," and shoots him right between the eyes. Gwyn appears from the surrounding woods and tells her two men to kill Nick's men.
Later at home Marlowe