The old saw about finding a needle in a haystack befits Darius Marder’s documentary “Loot.”

The “needle” in this case is booty stolen during World War II by two American GIs in unrelated instances.

They hid the loot — a fortune in jewels and three samurai swords — in Austria and the Philippines, respectively.

More than 60 years later, the geezers turned to Lance Larson, a used-car salesman and amateur treasure hunter, in hope of recovering their troves.

Directed by Marder, a Brooklynite, “Loot” is less an adventure yarn than a character study of two old guys with fading memories and improbable dreams.

As such, it is intriguing but hardly a treasure.