Few authors and/or historians have anything good to say about Rasputin, chiefly painting him as a demon incarnate. Rasputin was indeed a scoundrel, a charlatan, and inadvertently helped to bring about a tragic doom for the Romanov dynasty; however, he did (for his own reasons) intermittently help certain people for whom all hope seemed to be lost. Author/Historian Colin Wilson raises these more positive points in this 1964 240-page book.
One of the big problems with Rasputin books has been that about half of these authors bear some agenda, either for or against Rasputin. A clear example would be one which was written by Rasputin's daughter: Rasputin: The Man Behind the Myth. Yet another was written by the nobleman who actually murdered Rasputin: Rasputin: His Malignant Influence and His Assassination. It's clearly an objective of Yussupov's book to justify his actions in killing the infamous monk.
While Wilson's book is pretty good, he relies heavily on an early work which I (and many others) consider to be the definitive Rasputin book: Rasputin the Holy Devil, first published in 1927. It's equally clear that most other credible Rasputin books have also gleaned liberally from René Fülöp-Miller.
As Wilson points out, Rasputin was viewed differently by assorted people. To many of the poor he was a gifted saint. To the members of the Russian Duma he was anathema. To the Tsarina Alexandra he was sent to her family by God.
The latter idea emerged from the young Tsarevitch's (Alexis Romanov, heir to the throne) near death episodes from hemophilia, a disease which he inherited from his Great-grandmother, Queen Victoria. The Tsarina would call in Rasputin at times when the Tsarevich was near death and the Monk would "heal" the lad, seemingly through religious powers that he possessed.
Rasputin's other side was rampant debauchery. While he avoided vodka, he caroused incessantly under the influence of wine, raped any number of women, never bathed, and so on. The monk's philosophy was essentially this, according to Wilson [paraphrasing]: Vanity and pride being sins in the eyes of God, what better way to vanquish these personal traits (especially in women) than through defilement and debasement [rape]?
In the end, it became clear to thinking Russians that Rasputin would have to go, given his great influence with the Tsar and the Tsarina. Russia was being ripped apart by World War I, the masses were starving, and Rasputin was indirectly in control of the government. A conspiracy was ultimately formulated involving Prince Felix Yussupov (the Tsar's nephew) as the point man, and who at last murdered Rasputin first by poisoning him, then by shooting him, and then by drowning him to finish the job.
Wilson is quick to point out factual mistakes of other authors but his own book is a little flawed in places as well. For example, he mentions that the Tsar's daughter, Anastasia Romanov, somehow escaped the family's mass murder by the Bolsheviks which we now know is not true -- she died with her family.
But such glitches were common in books written prior to the fall of the Soviet Union when access to historical records and eyewitnesses, particularly involving the sensitive Romanov files, were totally off limits. And Wilson's account is independent and pretty much free of agendas.
If I were particularly in search of a book on Rasputin that was both factual and provided the social and political backdrop in which Rasputin operated, I'd go with Nicholas and Alexandra which reads like an epic novel. Still, if you have acquired Wilson's book, you'll get a good sense of the many facets of Grigory Efimovich Rasputin, the so-called "Mad Monk."