Transcendence has big, highly relevant ideas and a story that is a little bit too big and broad on top of it. Your enjoyment of it will likely come down to what degree the presence of the former makes you willing to forgive the latter. Johnny Depp plays Dr. Will Caster, a gifted artificial intelligence researcher who, primarily at the urging of his wife Evelyn (Rebecca Hall), uploads his very consciousness in to a supercomputer after a would-be Neo-Luddite assassin wounds him with an irradiated bullet, giving him mere weeks to live.

The Casters are the beating heart of the movie, even if one of them, Will, exists only as an avatar after his digital consciousness is successfully uploaded and online. It is Evelyn's fear of losing her husband that spearheads their decision to hole up in an abandoned warehouse and work feverishly toward preserving some piece of Will. And it is Will's calm, cool genius that makes achieving that a viable possibility. Alongside them as they work is a close friend and colleague, Max, who represents what amounts to the film's conscience, at least at the start. Played by a brooding and serious Paul Bettany, Max warns Evelyn of the dangers in bringing Will's digital consciousness online. There is no way to be sure it is actually him, he cautions. Once he's plugged in to the Internet -- processing more data in an hour than a human being could in its entire lifetime -- he'll possess limitless power.

He's not wrong, but he may not be entirely right. After successfully preserving Will's mind and narrowly escaping an encounter with the pseudo-anarchist group that first targeted him, Evelyn relocates to a dilapidated, barely inhabited desert town in Nevada as Will's power is growing. Seeded by money Will transfers to her control, construction begins on a massive underground structure where Will conducts research, grows even more powerful and yet still seems stuck on connecting and comforting an increasingly skeptical Evelyn. The location of the Caster compound -- beneath rows and rows of solar panels -- and its clean, white, hermetically sealed interiors clash, further accentuating a film that is determined to straddle the line between humanity and what might be the next phase of evolution.

Indeed, exactly what is left of Will's humanity provides most of the tension in the film. Evelyn's frustration with her inability to physically connect with her husband -- the limit of his voice and a two-dimensional image of him -- transforms in to unease as he begins to compensate for that shortcoming with his newfound and machine-like power. Evelyn drinks wine alone and in the dark in her husband's compound, only she is only half alone. There is Will's avatar trying, but never quite succeeding, to give Evelyn what she needs. In the background, there is a servant pouring her favorite wine. Hall provides the angst, while Depp provides either boundless optimism or utter tone deafness in what make up the film's best scenes.

Eventually Will's exponentially expanding power simply inspires pure in his wife when he exhibits a hive-mind-like control over some of the subjects upon whom he was worked medical miracles. It is at this point that Bettany, the leader of the Neo-Luddites (Kate Mara), a fellow scientist (Morgan Freeman) and an FBI agent (Cillian Murphy) re-enter the main thread of the film, attempt to convince Evelyn that something is terribly wrong with Will and try to take him offline. It is also at this point that Bettany seems most superfluous; Evelyn has long since supplanted him as the film's conscience.

Indeed, it's a pity that they all showed up again. The scenes involving Depp and Hall crackle with quiet intensity and philosophical mystery. What defines us as human? It is something more than our minds, Transcendence seems to be saying, but it never really settles on an actual answer. It might even be that, in an age of technology, it is our limitations that define us to some degree.

But when Bettany returns to the fray, bringing with him a bunch of noticeable stars that don't really inject the film with much energy, much of what makes Will's burgeoning power so interesting gives way to a fairly straightforward ticking-clock conclusion. Had Transcendence been a bit more comfortable in its skin -- a bit more willing to be inconclusive -- it could have been great. As it is, director Wally Pfister delivered a mostly satisfying bit of science fiction that falls short of being a classic.