I genuinely don't understand what the author wanted to achieve with this book. Large parts were just basic facts about the case: where the victims were found, who found them, details from the autopsy, witness-statements and so on. This part is quite well done and if you are unfamiliar with the details of the Ripper-murders this book does gives quite a good overview.
However once you get to the authors own theories it all becomes...questionable. The author names various people that have been suspects and gives his opinions on the likeliness of them really having been the Ripper. He often raises some good points but his research is hardly as new and ground-breaking as he claims in the introduction as many of the points have been raised long before. I also question how useful it is to spent a whole chapter on a guy who has been imprisoned and on a different continent at the time of the murders. It feels like he just needed to fill pages before he came to his suspect of choice: MJ Druitt...he doesn't dedicate much more pages to him than to those he considers unlikely suspects. His theory is solely based on the facts that
a) Druitt committed suicide shortly after the last murder
b) he left a note saying 'I fear I would become like mother' and his mother had been institutionalized in a mental asylum shortly before (he does not mention if he made an effort to find out why exactly Druitt's mother had been institutionalized, e.g if she had been violent towards others, in which case that part of the theory might have half a leg to stand on or if the family just saw a danger of her hurting herself/not being able to care for herself anymore in which case it would all be rather far-fetched)
c) from looking at photos of Druitt and from the wounds the Ripper's victims received he concludes that both must have been left-handed. He does make some good arguments for both of these theories but even if we accept both it is a rather thin argument.
d) Druitt has been included in the Macnaughten Memorandum...and at this point it simply gets really weird because he admits that the Memorandum is full of mistakes (it gets Druitt's age, job and date of death wrong) but for him that's a proof that Macnaughten must have known more than he said but couldn't tell it because Druitt was already dead and you can't put a dead man on trial (John Williams would like to protest)
He then goes on to talk about various possible Ripper-letters and how likely it is that they were genuine. Like with the suspects he makes some good, if not new, points but also dismisses many letters that announced more murders because there were no new murders after Mary Kelly, completely ignoring the possibility of the Ripper dying/being injured in an accident or being arrested for an unrelated crime, something he hardly would have mentioned in the letters.
Then it gets really odd because at the end he pulls another suspect out of his hat: John Kelly, Catherine Eddowes' partner. He throws some facts(?) at the reader that might have made compelling case if he elaborated a bit more and given sources for the claims he made but he doesn't which makes the chapter pretty useless.
All in all really not a book you need to read. If you're looking for a good overview you're better of with e.g. Whitehead's & Rivett's Jack the Ripper.
Finally a word to the cover which is somewhat problematic. I don't want to blame the author for the cover-designers mistakes but putting pictures of possible victims on the cover that are then dismissed in book by the author is...well. If you're apparently stealing those pictures online it's even worse.