Leeson's own research is embedded throughout the book, as you might expect. Many of the topics covered have relevance to modern times as well, but Leeson surprisingly avoids drawing the reader's attention to this until almost the end of the book:
Was Norman England's judicial system, which decided property disputes by having litigants hire legal representatives to fight one another physically, less sensible than contemporary England's judicial system, which decides property disputes by having litigants hire legal representatives to fight one another verbally?
Is contemporary Liberia's criminal justice system, which sometime uses evidence based on a defendant's reaction to imbibing a magical potion, less sensible than contemporary California's criminal justice system, which sometimes uses evidence based on a defendant's reaction to being hooked up to a magical machine that makes squiggly lines when her pulse races?
How about Renaissance-era ecclesiastics' tithe compliance program, which used rats and crickets to persuade citizens to pay their tithes? Any less sensible than World War II-era US Treasury Department officials' tax compliance program, which used Donald Duck to persuade citizens to pay their taxes?The book makes use of an interesting narrative device - it is presented as a tour through a museum of the weird. Some readers might find that approach a little distracting. I found it quirky and an interesting way to present the material. It wasn't necessary though - based on Leeson's earlier book I'm sure he could have written an equally interesting book without resorting to creating fictional tour characters to pose questions.
Overall, the book possibly isn't going to teach you a lot of economic principles, but it will show you how economics can be used to explain some seemingly weird practices (some contemporary, many historical). If you are into the quirky or weird, or just want to see economics pop up in unusual situations, then like The Invisible Hook this book is a must-read.