MacFarland doesn't like it when one of the "invisible people" gets accused of a crime. Innocent or guilty, it doesn't matter – the system is weighted against them. MacFarland becomes suspicious that the police have the wrong man when he learns that the suspect—an old man named Isaac Dawes, a man who suffers with a bad skin condition—is accused of killing his best friend. When Lord Bozworth, the leader of the homeless community in Denver, asks for MacFarland's help in freeing Isaac Dawes, how can MacFarland refuse?

The Impetuous Intruder is the ninth book in the Hot Dog Detective series. Each book can be read independently, but if you want to read them in order, just follow the alphabet.