An insatiable pursuer of women, Frank Sinatra ended up treating most of them very badly, but he had a soft spot for Marilyn Monroe, especially towards the sad end of her short life. Although he had casually encountered her in earlier years, it wasn't until the spring of 1961, 15 months before her death, that she began to frequent the singer's Palm Springs mansion.
At this juncture, she was overweight, frequently drunk and careless about her personal hygiene, yet although Sinatra found this last a turn-off, it didn't stop him having a sexual relationship with her. He also berated her in front of others ("Shut up, Norma Jean, you're so stupid, you don't know what you're talking about"), but he seemed genuinely concerned about the fragility of her psyche and, at one point in the following months, he even considered marrying her - if only to save her from herself.
You'll find this information in the second volume of James Kaplan's mammoth biography of the singer - its 980 pages exceeding by 200 pages his 2010 first instalment, Frank: The Voice, which came to a close with Sinatra's 1954 winning of an Academy award and his losing of Ava Gardner.
Gardner was the woman who taught Sinatra "how to sing a torch song", even if "she taught him the hard way". Indeed, in Kaplan's trite phrasing, "he would never get her out of his system", though in this second volume, we find him attempting to do so with scores of famous women and with hundreds, maybe thousands, of hangers-on, groupies and prostitutes.
And so, we read of the relationships, most of them fairly fleeting, with Gloria Vanderbilt, Lauren Bacall ("As a couple, we were combustible," she wrote in her memoir), Kim Novak, Anita Ekberg, Lee Remick, Juliet Prowse, Angie Dickinson, Judy Garland and Peggy Lee - to name just a few of his more starry lovers.
And there was also his relationship with Judith Campbell, whom he shared with John F Kennedy and with mob boss Sam Giancana.
Indeed, there's much here, and at somewhat tedious length, about his mob associations, though little that hasn't been documented in the scores of other Sinatra biographies, but Kaplan vividly evokes some other aspects of the singer's life, not least his fluctuating friendships, some of them terminated in fury over real or imagined slights - falling out, at various times, even with such close Rat Pack buddies as Dean Martin and Sammy Davis Jnr.
In fact, his unpredictable moods were so scary one of his oldest buddies, comedian Shecky Greene, who had a made a retort that angered him and was subsequently done over by goons, recalled that "the air was volatile and violent around him all of the time". (In later years, Greene quipped that "Sinatra saved my life in 1967. Five guys were beating me up and I heard Frank say 'That's enough'." However, comedian Don Rickles somehow escaped Sinatra's wrath when Rickles introduced him to a Miami nightclub audience with the words "Make yourself comfortable, Frank - hit somebody").
There were other fallings-out, too, though not all of them of his own choosing - the Kennedys coldly and irrevocably distanced themselves from their mob-tainted, party-animal pal once JFK became president - Sinatra's valet, George Jacobs, recalling that his boss suddenly "went from being the First Friend to just another greaser from Hoboken". Jackie Kennedy, for her part, had always loathed him.
And Kaplan's book shows there was much to loathe, with even Nelson Riddle, the arranger he most trusted and admired, declaring him the "one person in this world I'm afraid of". Indeed, he seemed to have been a man of alarming appetites and insecurities, eaten up with resentment and paranoia and capable of vicious cruelty as well as genuine kindness.
What makes his life interesting, if perhaps not at Kaplan's 1,700-page length, is that it reflects the social, political and cultural times of mid and late-20th century America more than that of any other celebrity icon, and so what you're reading is almost a biography of the age in which he lived.
What's missing, though - and this is really all that matters - is a sense of the artist whose recorded output transcended his tawdry life. He was the greatest popular male singer of the century and an incomparable interpreter of the American songbook, but Kaplan is not adept at describing his unique gifts.
And, so, while lovers of his great Capitol albums of the Fifties and Sixties recordings with his own Reprise label will be fascinated by Kaplan's accounts of the studio sessions that produced them, they'll have to look elsewhere for a proper appreciation of the alchemy that turned even the tritest of songs into something unforgettable.
"Never once a breach of taste," Noel Coward said of him, "never once a wrong note," but beyond the unerring musicianship, there was the voice itself, along with a feeling for a song's lyric that no other singer has ever come near.
Perhaps all this is not even definable in words - in which case, we're fortunate that the recorded legacy is there for anyone with ears to hear.