Hustling tourists in Peru for a quick buck, rugged American rogue Harry Steele (Charlton Heston) sees a chance for a big score when he finds a mysterious sacred stone that might lead the way to an ancient Incan treasure. The older and even more unscrupulous Ed Morgan (Thomas Mitchell) also wants to get his hands on the gold but his hired gun fails to intimidate the resourceful Harry. When beautiful European refugee Elena Antonescu (Nicole Maurey) asks for Harry to help her escape to the USA he agrees only because it provides an opportunity to steal a plane. Together they fly down to an archaeological site at an Incan temple where a team of scientists and a crowd of Peruvian locals are seeking the sacred treasure. Harry and Elena inveigle themselves with the archaeologists only to find the relentless Ed Morgan is also at the scene.
Secret of the Incas might have gone down in movie history as a fairly innocuous adventure yarn had not numerous film buffs noticed certain similarities with another Paramount production made almost thirty years later: Raiders of the Lost Ark (1981). Not only is Charlton Heston costumed in much the same iconic ensemble (brown leather jacket, tanned trousers and Fedora hat) as Indiana Jones but a key sequence wherein the sacred stone triggers a device that illuminates an ancient tomb with a shaft of light surely inspired the similar scene in that seminal Steven Spielberg film. Anyone hoping that the similarities also extend to a high-octane concoction of thrills and spills will come away disappointed though. In his last feature film before switching to a prolific television career director Jerry Hopper, who previously directed Heston in likeable western Pony Express (1953), is more concerned with exotic intrigue and splashes of local colour than white-knuckle action.
In fact long before Harry and Elena reach the archaeological dig the first forty-five minutes of the movie are mildly closer in tone to Casablanca (1942): cynical American who sticks his neck out for nobody reluctantly helps pretty European escape an oppressive regime, in this instance Communists instead of Nazis. Big Chuck is at his most rugged and affable here which helps given Harry is quite shady for a Fifties movie hero. Not only does Harry scam tourists but the film implies he also seduces the odd spinster for extra cash. Indeed a strong sexual undercurrent flows throughout the film as we learn lovely Elena is escaping her past as a prostitute in Romania while her arrival at the archaeological site sets the scientists practically slavering over her beauty. Much to the displeasure of inexplicably bitchy tribal queen Kori-Tica played by Peruvian singer Yma Sumac. In a strange touch of racism the film makes a big deal out of how repulsed the Peruvian ladies are by Elena's milky-white skin, though she is never less than nice to them.
Co-written by Sidney Boehm, who wrote The Big Heat (1953) and When Worlds Collide (1951), and Ranald MacDougall, who scripted Mildred Pierce (1945) and the superior The Naked Jungle (1954) which also stars Heston, the plot boils down to a battle for the soul of Harry Steele. In the villainous but faintly pathetic and semi-sympathetic Ed Morgan, Harry glimpses a vision of his future while in the altruistic corner we have kindly Dr. Morehead played by Robert Young. In his last film role before a long stint on television as Marcus Welby, M.D. Young does not get a whole lot to do. Yet his pipe-smoking, gentlemanly archaeologist proves far and away the most engaging character in the movie. He also provides the third point in a very mild love triangle after proposing marriage to Elena. In a genuinely touching scene Elena is so moved by his decency she can no longer play her part in Harry's scheme, though the film leaves us in no doubt as to which man she will choose.
Though the dialogue is snappy and very well crafted the plot ambles along without yielding that many thrills. By way of compensation Hopper includes plenty of local colour (the film supposedly kicked off a boom in tourism in Peru) and operatic musical numbers from Yma Sumac. She sings in a very high register that is shall we say an acquired taste. Guard your ear drums.