Strictly speaking, what we have here are 2 novellas about Garan and 2 unrelated short stories, rather than a novel, although the novellas are titled merely 'part 1' and 'part 2' rather than being given their original names in the table of contents. (I'll rectify that here.) The Garan novellas are set in an alternate history of our own world, but the short stories are from the Witch World series; the settings are unrelated.
The "Garin" vs. "Garan" spelling issue is not a typographical error, incidentally. The modern-day character's birth name has the 'i' spelling and pronunciation, while the people of Tav and Krand render it the other way.
"Garin of Tav", a.k.a. "People of the Crater" (1947) - Garin Featherstone's 15 minutes of fame passed years ago, after leading a daring airstrike during a long war. But down-and-out pilots still have their uses during an Antarctic exploration, seeking a crater with unusual characteristics, only seen once before from the air. While this may sound like a clone of Doyle's THE LOST WORLD, it quickly diverges from that path. The story has an intriguing start, but the "tell" to "show" ratio is a little too high once we're introduced to the world of Tav. Several "death before dishonor" scenarios pop up that seem inadequately justified. Worth reading, but the follow-up story below is more to my liking.
"Garan of Yu-Lac" (1969, 1973) - The very beginning and ending of this story involve the Garin and Thrala of the present day, as she reveals to him the tale of an age long past in which they met once before. The tale in between is the first-person narrative of that other Garan, on the long-vanished world of Krand. As the offspring of a forbidden cross-caste marriage, Garan's life has been shaped by Krand's rigid caste system; the only life open to him was that of the military, and that only by a merciful decree of the Emperor. Now, secretly, he has raised his eyes to the throne at the Emperor's right hand - Thrala, the emperor's daughter, in hopelessness. But other, darker secrets infest Krand. Two other characters seen briefly in "Garin of Tav" also appear in this past-life scenario, and their behaviour in the first story takes on added depth.
Krand reminds me of the original Buck Rogers comics in terms of technology (not that the details are allowed to become obtrusive); that's actually a point in its favour, for me. Garan's personal problem is handled with great artistry, as are the more world-threatening issues.
"One Spell Wizard" - See Norton's MOON MIRROR. A humorous Witch World story, even though the manner of storytelling is typical of the series, of an unsuccessful wizard who deliberately takes an apprentice with a speech impediment - since he wants an assistant for small-time con jobs, rather than spellcasting.
"Legacy from Sorn Fen" - Like "The Toads of Grimmerdale" (with which it appears in LORE OF THE WITCH WORLD), this tale features a man who rose from obscure beginnings to lordship in a Dale left leaderless in the wake of the Invaders' War, but Higbold and Treyvan have little in common otherwise.