What a daft and twee thing “Nandor Fodor and the Talking Mongoose” is. And God help anybody trying to market this dry, eccentric comedy built around the charms of Simon Pegg, Minnie Driver, Christopher Lloyd and sci-fi author Neil Gaiman voicing a (possibly) imaginary “talking mongoose.”

Perhaps it was the “true story” nature of the tale, a real-life Hungarian-American parapsychologist on the “skeptical” end of the spectrum investigating assorted published (and BBC broadcast) reports of a chatty mongoose who’d taken up residence on a farm on the 1930s Isle of Man that dialed down the wacky here.

One gets the feeling that writer-director Adam Sigal, with nothing distinguished on his resume and nothing at all comic, left a lot of laughs on the table in conjuring up supporting players and casting them with reliable comedians and giving them amusing things to say and do.

But it’s an immaculately-realized period piece about a fine bit of humbug, with plenty of charm and a healthy appreciation for the paranormal lore it dabbles in. And if it isn’t hilarious, it will make you smile.

Pegg’s doubting Dr. Fodor character is visiting the UK when he’s summoned by an old parapsychologist (Christopher Lloyd) rivalwho suggests he look into something that stumped the older Dr. Harry Price — this farm and its celebrated talking mongoose the family that hosts him has named “Gef.”

“It’s the strangest case I’ve ever encountered.”

Yes, Price went to the Irving Farm on Dalby Mountain to see for himself. No, he didn’t actually “see” Gef.

“But I heard him…in the next room.”

Oh, and by the way, one of the members of the Irving family, daughter Voirrey (Jessica Balmer) is “an accomplished ventriloquist.”

Fur from the animal was provided by Gef and tested by a university biologist who deemed it more likely from a dog than a mongoose.

And all of this has Fodor repeatedly raising an eyebrow, knocking back another belt from his drink, and then relaying this seemingly-obvious fakery to his assistant Anne (Driver).

But Dr. Price weaves this account of a humbug that he actually believes in around anecdotes about Harry Houdini’s (Edmund Kingsley) years of debunking frauds and fake spiritualists, leading the two men to drift into thoughts about matters existential and the nature of faith, belief and delusion.

Since the Irvings don’t seem to provide an obvious answers as to “why” they’re insisting all this is real — there’s no profit “motive” — there’s nothing for it but for over-dressed Fodor and Anne to motorlaunch over to the Isle and see and hear for themselves.

On meeting the Irvings — played by Tim Downey, Ruth Connell and Balmer — Fodor rolls his eyes at the Tinkerbell nature of this “Earthbound spiritual being,” Gef. Fodor must announce “I believe” into whatever barn, wall-crawlspace or cave Mr. Irving insists Gef was “just here” in. Because “Gef’s probably watching us, right now.”

Meeting the town drunk (Paul Kaye) down at the otherwise empty local pub tips Fodor that this bloody mongoose is “clairvoyant,” too, telling people things in person or over the phone that your average “Earthbound spiritual being” wouldn’t know.

All of Fodor’s huffing about “any real evidence” kind of goes by the board as one and all “believe.” Even Anne starts to buy in, even after she’s gotten a ventriloquism lesson from the “accomplished” Voirrey.

The man of science hears the “Oh, he just left” excuses. And then he hears this elfin voice on the phone (Gaiman), which tells him something which unnerves him, no matter how inane the viewer recognizes it to be.

No, there’s nothing much to any of that, although the odd embarrasing bit amuses — about why Anne hasn’t married, why she hasn’t taken up with her paranormal boss and made use of those “fine birthing hips” — and the occasional incredulous stare from Pegg over what he’s being asked to consider is possible when “facts” and “reason” and “evidence” render impossible is worth a grin.

Every anecdotal flashback engages, and as they’re all related by Lloyd, Pegg or Kaye (“Game of Thrones”), they serve to ensconce us in this quirky place and time, when respectable newspapers covered the hell out of absurd nonsense like this.

Maybe “Doctor” Fodor is missing out on that leap of faith it takes to “believe.” Maybe the parade of irrational folks around him are onto something, as the farm’s hired hand (Gary Beadle) suggests, even though he and Fodor know there isn’t anything there.

That kind of goes for this film as well. Whatever isn’t here somehow adds to the charm of what is. That won’t be for everyone, but if you’re on this wavelength and have a soft spot for these players, “Nandor Fodor” could give you a grin, with or without that talking mongoose.

Rating: PG-13, smoking and a spot of profanity, wot wot?

Cast: Simon Pegg, Minnie Driver, Paul Kaye, Ruth Connell, Tim Downie, Jessica Balmer, Edmund Kingsley and Christopher Lloyd, featuring the elfin voice of Neil Gaiman.

Credits: Scripted and directed by Adam Sigal. A Saban Entertainment release.

Running time: 1:36