Knock knock.

Who’s there?

The mysterious Men in Black.

The mysterious Men in Black who?

We can’t say. Then we wouldn’t be mysterious.

And we wouldn’t have the fun of puzzling out who – or what – the so-called “Men in Black” are. If you only know these enigmatic visitors – referred to among the alien-spotting literati simply as MIB – through the campy Hollywood films of the same name, you’ve only got a small part of the story.

Veteran UFO-ologist and chronicler of the all-around-weird Nick Redfern lays it all out for you in his latest book, The Real Men in Black: Evidence, Famous Cases, and True Stories of These Mysterious Men and Their Connection to UFO Phenomena.

The Men in Black are reportedly a trio (though they sometimes go rogue and work alone) of anonymous dark-garbed men who show up at the homes and businesses of individuals who are active in the UFO community, or who have recently reported a sighting of an extra-terrestrial spacecraft or visitor. According to the lore, these men seldom identify themselves, speak in hushed tones, and often hide their faces behind sunglasses and under the brim of their fedoras, even in dark settings. Reportedly, these shadowy ambassadors from parts unknown issue dire warnings to their hosts, telling them to forget they’ve ever seen anything, and not to talk further to any officials about whatever they might have seen.

Many of the accounts Redfern cites of MIB visits also include supernatural elements: the MIBs can read minds, move through walls and doors, disappear into thin air, and have facial features and bodies more alien than human. Despite the outlandish nature of some of these “encounters,” the whole MIB phenomenon has become an entrenched urban legend. Many in the amateur UFO-watching community claim their existence as an article of faith.

Redfern, who knows this community well, has written an entertaining book but one that falls far short of the promise in his subtitle. Much of the “evidence” he cites is specious, unconfirmed, third-party rumor, passed from one UFO fan to another over the years. The parade of Wiccans, time travelers, and parapsychologists who comprise his witness list tends to undermine any serious basis for belief that these MIB really exist. Halfway through the book, I found myself asking “Does even Redfern belief in this kookiness?”

The second half of the book makes clear that he himself remains skeptical of many of the accounts of the MIB. But it’s in that second half of the book, where he moves from relating accounts of appearances of the MIBs in the past fifty years to exploring the theories that would explain the phenomenon that Redfern’s book really gets interesting. (Part One of the book is called “The Case Files” and Part Two is called “The Theories.”) Redfern puts forth a variety of explanations that would help explain why some people have claimed to encounter the MIB. Some of his explanations seem plausible: the MIB are the product of hallucinations, or the result of a hoax. Other explanations seem as far out as his alien visitors: the MIB are time travelers, or manifestations of the devil. (“The idea that the UFO presence on our world may have demonic origins is not a new one.”)

If you are entertained by books about alien abductions, Bigfoot, the Loch Ness Monster and time travel, you’ll probably like The Real Men in Black. If, however, you’re looking for absolute proof before you call the FBI that the suspicious trio of dark-suited men hanging around your apartment lobby are really alien agents, you might want to ask them for their business card first, just to be sure.