KINGMAN, Alberta (AP) — Larry Asp grew up playing shinny outside in this tiny rural town he calls home again after 40 years away. Since returning, he also holds the keys to the outdoor “Rink of Dreams” that gives the 90 local residents the chance to skate outside during the keen Canadian winters.

Out here on the prairie an hour’s drive southeast of Edmonton, the ice in the former “Lutefisk Capital of Alberta” doesn’t seem to freeze as long as it used to, not like when Asp was a kid. He unlocked the doors to the rink, which in late September was simply dirt after a summer of hosting barrel racing and other equestrian events, and gazed into the wind-swept distance.

“We’re kind of at the mercy of the elements,” said Asp, a retired member of the Kingman Recreation Association board. “In the springtime because of the (rink’s) white boards and the sun, it starts melting back from the boards pretty quickly. You’d be really lucky if you got four months out of it.”

Nearly half-a-century ago, an event took place that has captivated and confounded people ever since. Something so outlandish, so unbelievable, so inscrutable that it can’t help but be fascinating even now, almost 50 years since it happened.

All I have to say is a name: D.B. Cooper. If you know, you know. If you don’t, well – he’s the man who, back in 1971, executed what remains the only unsolved skyjacking in the history of American aviation. He leapt into the night carrying $200,000 dollars, the plane in the skies over Washington state … and was never seen again.

“The Mystery of D.B. Cooper” – written and directed by John Dower – is a documentary that offers its viewers a potential solution to its titular question. Or rather – four solutions. Dower’s film features four primary subjects, each of whom shares the unshakeable belief that they know who D.B. Cooper was.

And they have four different answers.