"Contagion" opens with the sound of Beth Emhoff (Gwyneth Paltrow) coughing and wraps around to end one day earlier at the unsuspecting moment that decides the fate of her life. A global marketing rep from Minneapolis on a business trip to Hong Kong, she initially assumes her illness is due to jet-lag, blissfully unaware that in just four days she will be dead—one of the first victims of a nationwide pandemic that will ultimately claim millions upon millions of lives. As the title suggests, the spread of the virus is highly contagious, every instance of physical contact another chance to infect several more people, the numbers multiplying across portions of the globe at an exorbitant rate. Watching the film, directed by Steven Soderbergh (2009's "The Girlfriend Experience") and written by Scott Z. Burns (2007's "The Bourne Ultimatum"), it is easy—and sobering—to imagine how something could potentially happen exactly like this, and on such a massive scale. Therein lies the grim beauty of "Contagion," which avoids sensationalizing its subject in lieu of treating it with grave realism and fatalistic forthrightness. No one is safe, not even the A-list stars who make up much of the ensemble.

As conceived by Soderbergh and Burns, there are no lead protagonists so much as hand-picked key players among many, the whole of them standing in for a microcosm of the world. By the time Beth returns home, she is very sick, and the severity of her symptoms only increase. Her husband, Mitch (Matt Damon), is one of the slim majority to be immune from the virus, but their six-year-old son Clark (Griffin Kane) is not so lucky. Twenty-four hours later, Mitch has been widowed, lost one of his children, and as more and more is learned about Beth's illness, the more he also uncovers about the affair she was having in Chicago during her flight layover. All of this would be too much to bear for anybody—thankfully he still has his teenage daughter from a previous marriage, Jory (Anna Jacoby-Heron), who returns home from her mother's and insists on staying with him—but even more disquieting is the infectious, damning ripple effect Beth's decisions have caused the planet at large. With medical and health professionals struggling to track and contain the virus while beginning the long, laborious testing process of finding a vaccine, the death toll rapidly mounts and hysteria sets in amidst quarantined zones.

"Contagion" is frighteningly believable, businesslike, super-smart and never less than riveting. The gravity of the situation demands that there is not much room for frivolous subplots and the like, but director Steven Soderbergh nevertheless keeps sight of his characters' humanity. They aren't just walking encyclopedias of exposition, but when they do talk to each other as experts in their field, they don't dumb down their dialogue to appease the masses. As Mitch copes with the whirlwind of his current devastating circumstances, CDC Deputy Director Ellis Cheever (Laurence Fishburne) sends Dr. Erin Mears (Kate Winslet) to Minneapolis to investigate Beth's case, not fully prepared for the cost that her demanding job is about to have on her. For World Health Organization epidemiologist Dr. Leonora Orantes (Marion Cotillard), her destination is Hong Kong, where she hopes to research Beth's every move during her overseas trip so that she can begin a list of the potentially infected. Unbeknownst to Leonora, her assignment is about to take a sharp u-turn of its own. San Francisco-based freelance blogger Alan Krumwiede (Jude Law) is thrown into the spotlight for posting the first video on the Internet of one of the infected dying, a coup for him that he decides to take to an opportunistic extreme by accusing Cheever and the CDC of keeping a known antidote from the public's grasp. Meanwhile, lab researchers Dr. Ally Hextall (Jennifer Ehle) and Dr. David Eisenberg (Demetri Martin) continue to test for a vaccine, knowing full well that sacrifices will need to be made and critical months are bound to pass before they can get one approved.

The premise itself is sure to draw more than a cursory comparison to 1995's "Outbreak," but "Contagion" stands as the superior, less commercially reliant effort. Whereas "Outbreak" tried to pep things up with helicopter chases, a romantic subplot, and a happily saccharine deus ex machina finale, this one recognizes that the real drama should deservedly remain focused on the cataclysm at large. Without opening credits or even a title card, Soderbergh leaps with fearless abandon into a fearful avalanche that traces the way in which a strain of infection can so easily accumulate and in no time cause an epidemic. Germaphobes will be left petrified for the 100 minutes that follow and the rest of viewers will likely not be able to escape without a tinge of queasiness at the thought of ever coming in contact with another person, door handle, or elevator button again. Jumping back and forth from U.S. locations to China to Japan to England to Switzerland and so on, the picture procures a necessary grand scope, then adds urgency with its momentous pacing and a complimentary, synthesizer-heavy, thoroughly unusual music score by Cliff Martinez (2011's "The Lincoln Lawyer") that ranks as one of the year's most memorable.

Performances are of the highest class possible. Laurence Fishburne (2010's "Predators") is convincing as Dr. Ellis Cheever, giving the CDC Deputy Director a command and intelligence one would expect, but also a solid, man-of-his-word quality not often seen in on-screen leadership roles. As the workaholic Dr. Erin Mears, Kate Winslet (2008's "The Reader") is deeply affecting, navigating stressful untouched water and holding firmly onto an empathy that, sadly, is not going to help her in her immediate fight. Everything that needs to be known about her is unforgettably revealed in one of her last moments: an attempt at giving a blanket to a dying patient under dire circumstances best not to be discussed. Jennifer Ehle (2010's "The King's Speech") and Marion Cotillard (2010's "Inception") bring selfless resolve to Dr. Ally Hextall and Dr. Leonora Orantes, the former especially good in a scene she shares with her ill father and the latter receiving an arc that is touching in its unforced eloquence. Even small turns from such veteran character actors as Elliott Gould (2007's "Ocean's Thirteen"), John Hawkes (2010's "Winter's Bone"), and Enrico Colantoni (2002's "Full Frontal") make an impact, all of them aiding to the full picture in the same way the ensemble of, for example, 2005's "Syriana" did.

If there is an emotional throughline to the narrative tapestry, it is the internal path taken by Matt Damon's (2011's "The Adjustment Bureau") Mitch Emhoff, keeping his strength and morale up for his daughter while putting on holding the unbearable grief of losing his wife and son. Those kinds of feelings can't be buried without being dealt with, and when Mitch's breaking point occurs, Damon lends it all the dignity and raw poignance it deserves. Looking at pictures his wife took on her last business trip, he both intimately recognizes the woman staring back at him and wonders of the things he didn't know about her that he will now never get the chance to learn. Gwyneth Paltrow (2010's "Iron Man 2"), as ill-fated wife Beth, haunts the proceedings like a specter that refuses to go away.

"Contagion" is vast in sight, yet trim in length, a noticeable gap calling attention to itself when "Day 26" segues to "Day 131" without any explanation of how certain characters have managed to survive the bleak interim. A few others, like Cheever's wife Aubrey (Sanaa Lathan), serve their purpose, but are so minimally conceived that little is done with them once they're established. If the only next thing to be done is precisely what is expected, credit director Steven Soderbergh for the taut, uncompromising potency he has doused the picture in. Never does it appear corners have been cut in order to pander to mainstream audiences, yet, to be sure, there is hope as "Contagion" draws to a close. It can be seen in the impromptu prom that Mitch throws for his daughter at home, the sounds of U2's "All I Want Is You" a call of mourning for the unimaginable loss of life around them. It can be glimpsed in a crucial decision Leonora makes in her final scene, the value of truth winning out over safety. And, overall, it can be symbolic of the strength and compassion that the human race is capable of in the worst of times. Soderbergh makes this point, but doesn't wallow in it or use such an opportunity for a bunch of saccharine flag-waving. He's more astute than that, and his film is all the more honest because of it.