"If you're not good, the Ripper'll get you!"

That threat was enough to frighten my grandmother so badly -- she was born in Dublin in 1879, and so was 9 years of age when Jack the Ripper was cutting up in London -- that, 80 years later, she could still convey the fright of it to me. She grew up a very good little girl indeed.

But the truth is that she would have had to be an extraordinarily bad little girl to have warranted the Ripper's interest, because that rather rude gentleman limited his attentions exclusively to the prostitutes of London's Whitechapel district. He was handy with a scalpel, Jack was, and of a gruesome turn of mind, and a massive manhunt and flaming headlines did nothing to deter him. The rampage lasted several months and then, abruptly, it stopped.

But who was the famous Jack? Robert Bloch has a credible answer in his latest novel, "The Night of the Ripper."

Bloch, of course, is best known as the author of "Psycho," but his renown for that particular exercise has tended to obscure his other ac- Alan Ryan's newest book is the forthcoming "Dark Assortment," a collection of short stories.complishments. He has also written dozens of screenplays, nearly two dozen other novels and twice that number of short-story collections. He has been writing scary stories, in one form or another, for 50 years and, in fact, in 1943 he published a story, long since considered a classic of horror literature, called "Yours Truly, Jack the Ripper." It would have scared the Ripper himself. Bloch knows what he's doing, and I can't think of a single other writer working in this field whose "Ripper novel" I'd rather read.

It appears that we will never know with any certainty just who Jack the Ripper was, but theories abound. Bloch pays homage to all of them, including those of such modern authorities as Stephen Knight and Frank Spiering. Then, after leading us on a merry chase through fog-bound Victorian London, he produces an ingenious solution of his own, and if there is no hard evidence to support it, there isalso no way of refuting it. It may even send the experts back to their notes.

Bloch invents a young American doctor, Mark Robinson, who is studying at London Hospital, and quickly gets him involved in the hunt for the killer. Robinson is kept hopping through the whole book, what with his awkward love affair with a charming student nurse at the hospital and with the aid he offers to a London detective named Abberline. Abberline, growing more frustrated by the instant, suspects everyone in sight, including our young hero.

But Bloch provides glimpses of every possible solution, besides the tantalizing, and longstanding, suspicion that Jack was really the Duke of Clarence, Queen Victoria's grandson. Considering his skill with a scalpel, was Jack a doctor? Bloch provides a ripe candidate in a surgeon who likes to visit the slaughterhouse when he's not in the OR. But that's not giving anything away. Bloch offers so many possible paths for his hero's investigation that the reader's head will be spinning like poor Mark's.

Over the course of his career, Bloch's novels, in general, have been less successful than his short stories. He is, essentially, a short-story writer, and among the very best we have. "The Night of the Ripper" is a short-story writer's novel, but in this case that is an advantage. The book's episodic structure, tightly controlled by Bloch, permits him to range far afield in this complicated story, and yet to make perfect sense of it all in the end. It also permits him to introduce an enormous range of characters, including such real-life Victorian celebrities as Arthur Conan Doyle, John Merrick (the "Elephant Man") and Oscar Wilde. Within this structure, and with hundreds of short stories to his credit, Bloch can do more in 200 words to create a personality and advance the plot than many writers can Book World Stalking the Ripper THE NIGHT OF THE RIPPER By Robert Bloch Doubleday. 227 pp. $14.95 Reviewed by Alan Ryan

"If you're not good, the Ripper'll get you!"

That threat was enough to frighten my grandmother so badly -- she was born in Dublin in 1879, and so was 9 years of age when Jack the Ripper was cutting up in London -- that, 80 years later, she could still convey the fright of it to me. She grew up a very good little girl indeed.

But the truth is that she would have had to be an extraordinarily bad little girl to have warranted the Ripper's interest, because that rather rude gentleman limited his attentions exclusively to the prostitutes of London's Whitechapel district. He was handy with a scalpel, Jack was, and of a gruesome turn of mind, and a massive manhunt and flaming headlines did nothing to deter him. The rampage lasted several months and then, abruptly, it stopped.

But who was the famous Jack? Robert Bloch has a credible answer in his latest novel, "The Night of the Ripper."

Bloch, of course, is best known as the author of "Psycho," but his renown for that particular exercise has tended to obscure his other ac- Alan Ryan's newest book is the forthcoming "Dark Assortment," a collection of short stories.complishments. He has also written dozens of screenplays, nearly two dozen other novels and twice that number of short-story collections. He has been writing scary stories, in one form or another, for 50 years and, in fact, in 1943 he published a story, long since considered a classic of horror literature, called "Yours Truly, Jack the Ripper." It would have scared the Ripper himself. Bloch knows what he's doing, and I can't think of a single other writer working in this field whose "Ripper novel" I'd rather read.

It appears that we will never know with any certainty just who Jack the Ripper was, but theories abound. Bloch pays homage to all of them, including those of such modern authorities as Stephen Knight and Frank Spiering. Then, after leading us on a merry chase through fog-bound Victorian London, he produces an ingenious solution of his own, and if there is no hard evidence to support it, there isalso no way of refuting it. It may even send the experts back to their notes.

Bloch invents a young American doctor, Mark Robinson, who is studying at London Hospital, and quickly gets him involved in the hunt for the killer. Robinson is kept hopping through the whole book, what with his awkward love affair with a charming student nurse at the hospital and with the aid he offers to a London detective named Abberline. Abberline, growing more frustrated by the instant, suspects everyone in sight, including our young hero.

But Bloch provides glimpses of every possible solution, besides the tantalizing, and longstanding, suspicion that Jack was really the Duke of Clarence, Queen Victoria's grandson. Considering his skill with a scalpel, was Jack a doctor? Bloch provides a ripe candidate in a surgeon who likes to visit the slaughterhouse when he's not in the OR. But that's not giving anything away. Bloch offers so many possible paths for his hero's investigation that the reader's head will be spinning like poor Mark's.

Over the course of his career, Bloch's novels, in general, have been less successful than his short stories. He is, essentially, a short-story writer, and among the very best we have. "The Night of the Ripper" is a short-story writer's novel, but in this case that is an advantage. The book's episodic structure, tightly controlled by Bloch, permits him to range far afield in this complicated story, and yet to make perfect sense of it all in the end. It also permits him to introduce an enormous range of characters, including such real-life Victorian celebrities as Arthur Conan Doyle, John Merrick (the "Elephant Man") and Oscar Wilde. Within this structure, and with hundreds of short stories to his credit, Bloch can do more in 200 words to create a personality and advance the plot than many writers can manage in 200 pages.

If the book has a flaw (apart from the publisher's terrible proofreading), it is in the superfluous headnotes, detailing a history of torture and mass murder through the ages, that only impede Bloch's otherwise fast-moving tale. "The Night of the Ripper" may well nudge out "Psycho" as Bloch's most popular novel. It is fast, tense, ingenious and great fun: a ripping good read. manage in 200 pages.

If the book has a flaw (apart from the publisher's terrible proofreading), it is in the superfluous headnotes, detailing a history of torture and mass murder through the ages, that only impede Bloch's otherwise fast-moving tale. "The Night of the Ripper" may well nudge out "Psycho" as Bloch's most popular novel. It is fast, tense, ingenious and great fun: a ripping good read.