The third time isn’t necessarily the charm with the latest adaptation of I Am Legend, Richard Matheson’s classic 1954 zombie novel. Previously filmed in 1964 (as The Last Man on Earth, starring Vincent Price) and 1971 (The Omega Man, with Charlton Heston), the book and all its film versions jump off from some sort of biological disaster that has killed most of mankind, leaving a handful of “normal” survivors, the rest having turned into marauding, night-crawling freaks.

This time out, the action takes place in New York (in the book, it was Compton, Calif.), where Dr. Robert Neville (a very buff Will Smith) is the last human alive in Manhattan, where he has holed himself up in a heavily fortified, and well-provisioned, Washington Square townhouse. Accompanied by his faithful dog Sam, the good doctor, who has a basement laboratory where he obsessively looks for a cure to the dreaded disease, roams the streets of Gotham looking for provisions and other humans. But he must be home and locked down before nightfall, when the ghoulies emerge from their dark hiding places.

Director Francis Lawrence’s film operates on two levels. It tries, with relative success, to show how enforced isolation can work on the psyche of a strong-willed individual. Smith’s character seems to be dealing as well as can be expected with his solitude, but the fact he has begun giving names and personalities to store dummies does not bode well for his future mental state. In all this, Smith remains his sympathetic self, an actor whose magnetism can overcome even the slightest material.

Where the film really shines, however, is in its utterly eerie evocation of an abandoned New York slowly but surely returning to its natural state. Herds of deer run wild through the streets, and Times Square is so overgrown, Neville is using the area as a cornfield. Scenes of the lone human and his dog zooming up and down a denuded Fifth Ave. and other major thoroughfares in a hot car are chilling and fascinating, as are shots of the Brooklyn and Manhattan bridges, which were blown up years before in an attempt to quarantine the island. Simply put, the CGI work and production design of this film are absolutely top-drawer.

But for some reason, the parts don’t quite mesh. Is it a zombie film? Is it a psychological drama? Is it a message of despair? Or one of hope? The novel ends on a fairly downbeat note, but its cinema versions have not really gone down that road. The fact is, Matheson wrote the book as an out-and-out zombie thriller, and even though Lawrence’s film is an honorable attempt to bring more depth and meaning to the tale, ultimately he probably should have opted for more gore, less grief.