I'll skip the plot recap and get right to the point: The River of No Return is one terrific read. 
 This book has so many elements that appeal to me as a reader. It's part historical fiction, part time travel fantasy, with heaping doses of mystery and romance as well. I was reminded in tone, though not really in content, of Deborah Harkness's books, A Discovery of Witches and Shadow of Night -- not that The River of No Return has supernatural characters, but rather because of the well-researched historical detail intertwined with a modern love story and mystery, the drama of two lovers having to struggle against sinister forces that they don't fully understand, and the passionate link between two people who probably have no business being in each other's lives at all. 
 The writing in The River of No Return is both elegant and fast-paced. As the characters inhabit different eras, their language and surroundings change as well, and it's vastly entertaining to see them adjust and readjust to the customs, manners, and dress of each world. I loved, too, the characters' obvious delight in the various sights and smells of the the different times. 
 I absolutely recommend this book -- and if you'd like to see my more long-winded (or what I'd like to call "thoughtful") response to The River of No Return, you can find it here.