The main selling point for Don Siegel's thriller was that it was shot, in Cinemascope, on location at the Grand Canyon. This was probably not as impressive as it could have been had a Cinerama camera not already been flown through the canyon several years earlier. Still, many people probably hadn't seen any Cinerama by 1959, so there was no doubt some thrill and novelty to seeing planes fly through and stuntmen cavorting on a cable car above the abyss. These thrills aside, Edge of Eternity is a pretty basic mystery story. It opens with a failed attempt at vehicular homicide at the canyon's edge, the intended victim eliminating his attacker only to be done in a few scenes later. It's up to Deputy Les Martin (Cornell Wilde) to figure out whodunit despite the distraction of speed-demon heiress Janice Kendon (Victoria Shaw). After leading him on a merry, picturesque chase early on, Janice provides Les an entry into her wealthy gold-mining family, including her crabby dad and her drunken brother. People get on Les's case for failing to crack the murder case quickly, but Janice's eye for fashion finally provides a crucial clue tying the victim, if not his initial attacker, to the mining interests around the canyon, ranging from gold to guano.
Siegel's writers try to keep things mysterious by having a later killing carried out POV camera = killer style, but it only looks awkward and evasive. Toward the end, the killer is revealed without anyone on the screen having deduced his identity from clues, though I suppose some in the audience may have guessed the culprit by process of elimination. His discovery sets up the big thrill climax on the guano car, but the thrill of actuality is undermined every time Siegel cuts from the long shot of the stuntmen to the studio close-ups of Wilde et al in front of rear projections. The location stuff is nice to look at, though, thanks to Burnett Guffey's cinematography, and seeing the juggernaut cars of the era in action is always fun. Even with the special attraction of the Canyon this is little more than a B picture, and as such its diverting enough without lasting long enough to waste your time.