Since 1997, young men have walked out of bars alone and turned up in rivers. Two retired New York detectives say the police have been calling murder an accident.

They have a name for it–serial murder. They have a map–the first thirty-five cases fell along one stretch of Interstate 94, from Michigan to Montana. They have smiley faces spray-painted near the water where the men went in, and a victim count that started at forty and eventually passed seven hundred.

The FBI says there is no evidence any of it is connected.

THE CONCRETE SMILED lays out the Smiley Face Killers theory the way its own investigators tell it–the van that followed Patrick McNeill down Second Avenue, the fly eggs in a body pulled from the East River fifty days later, the mother who would not accept that her son had simply fallen in. It gives the theory its best case, at full strength, without hedging.

Then it checks that case against the record.

What turns up is stranger than either side admits. The two cases the whole theory rests on carry no smiley faces at all. Its only living witness spent nearly twenty years inside a book no forensic journal ever reviewed. Four forensic arguments hold the theory up, and not one of them survives a look at the literature.

And yet the families are right to be angry. Postmortem screens do not routinely test for the drug everyone is arguing about. One retired homicide detective believes two or three of these deaths really were murders, waved off because a theory this loud made the whole category easy to dismiss.

Ninety-five sources. Every claim traced back to where it came from.

From Darren Marlar, creator and host of the Weird Darkness podcast.