After gunshots echo through the summer night on Mount Macedon, Detective Sergeant Zoe Mayer and her loyal service dog Harry race to the summit at first light. What they find looks like a grisly murder-suicide- an alleged fraudster named Piers Johnson, and his lawyer Antony Peterson, both dead from bullet wounds, a gun lying nearby.

Something about the scene doesn't stack up. There are plenty of suspects, but no one seems to be telling the truth. Zoe's instincts are ignited, as the pressure to find and charge the culprit becomes intense. And that's when Peterson's teenage daughter Sarah is snatched off the street. The Good Dog is Zoe's toughest assignment yet, a murderous conspiracy of greed, deceit and violence. She knows that Harry may be her only chance to crack the case.