"You begin every course with an "A" grade," a college professor of mine once said. "Whether or not that grade stays an "A" is entirely up to the effort you put into the class assignments and preparation for exams." I never forgot this nugget of wisdom. How lovely to know at the start of each term, your GPA is a solid 4.0. What great motivation to maintain an unblemished record.

So too, each new read begins with an "A", with 5 stars, as a 10 of 10. As the pages turn, however, it's the rare book that doesn't slip even a little from the lofty heights of perfection.

A Discovery of Witches starts out like an eager co-ed whose patent leather shoes are shined squeaky-bright, whose skirt pleats could slice a tomato, whose perky ponytail swings like a metronome each time she raises her hand to answer a question. Yet over the course of the term, your star pupil drifts away from her front row seat; an absence here and there becomes a disturbing trend of truancy. By the end of the term she is sitting in the back, her muffin top squeezing out over the top of too-skinny jeans, punching at the screen of her smartphone and whispering snarky-nothings to her BFFs - probably about your choice of shoes or your split ends. You take her flake-out in stride; you can't win 'em all - but it's hard not to be terribly disappointed by the promise of a good read gone sadly, cliche-ridden-ly, wrong.

Let's be honest here. You can't pick up a book featuring witches and vampires and expect Anna Karenina. I was hoping for a fun but intelligent read à la Kate Mosse's Labyrinth or Elisabeth Kostova's The Historian or Carlos Ruiz Zafón's The Shadow of the Wind or Connie Willis's Doomsday Book - all delicious, beautifully-written works of historical speculative fiction - to take me back across the Atlantic and through the inevitable nights of jet lag that follow transoceanic travel. Skimming the book jacket, the phrases "Deep in the heart of Oxford's Bodleian Library..." "...alchemical manuscript..." "...age old tensions between science and magic..." took me past my initial snorting at the witches and vampires aspect, which I generally skirt at wide berth.

And like a student determined to keep her grade a pristine "A", things started off swimmingly. It was all I could hope for in a curl-up-and-escape read: Oxford in resplendent Gothic-falling-leaves-cardigan-sweaters cozy glory, the Bodleian with its ancient manuscripts and secret corners, a handsome, if not frighteningly pale, anti-hero and a sassy heroine who adores books and early morning runs. Then the fun really gets rolling. Vampires with crack taste in wine! Non-human creatures practicing hardcore yoga! Occitan-speaking castle-dwellers making sandwiches deep in the heart of the Rhône valley!

But around page 200 the author jumps the shark. What was a fun flight of paranormal intrigue becomes a goopy, over-written romance. Without even the satisfaction of great sex to make up for lines such as "I like the way you smell," that pass for seduction between the undead and creatures who cry tears the size of softballs.

About this time, I began to trip over annoyances in the narrative. A solid "A" for atmosphere and attention-to-detail tumbled to "C" for crap editing. I can't imagine what this manuscript read like before it went under an editor's pen. It still contains so much drively, snively exposition by our reluctant-witch-heroine, Diana. The pace drags, then stalls, then the plot unravels completely. And our hero, vampire Matthew de Clermont (quite the best part of this story), inexplicably takes over the narrative at a couple of points early on, but then never again.

And our heroine? This scull-rowing, yoga-practicing scholar of incredible witchy talents requiring deep concentration and introspection? She is forever leaping and bounding, dashing and jerking, yanking and smacking. Or flipping back her shoulder-length, straw-colored hair. She wore me out.

Each time I came close to pitching it in, I was whisked away by private plane to the Auvergne region, or taken stag hunting by a vampire, or tossed down an oubliette by a Finnish witch - just enough to hold me until I passed the point of "don't quit now". Sheer will and a couple bouts of insomnia saw me to the sappy end.

It's all really too bad, for Harkness's writing snaps and sparkles when it isn't coated with romantic sludge. She has engaging passion for the speculative genre and its creepy, lush, sexy, crafty, timeless creatures. I could well-envision Diana and Matthew crossing geographic and time borders as a pair of other-worldly sleuths -- platonic, but brimming with unspoken attraction for one another. Instead, well, they are now a boring married couple. Although they had yet to consummate the relationship by the book's end, so I guess I can't give this an "F" for F*ing, since there isn't any.

I'll settle for "D", as in Degringolade.