Humans are frail creatures. As we try and cure the world’s diseases and protect ourselves from powerful forces, nature becomes harsher and keeps life in balance. Unfortunately, we humans too often have to battle our own stupidity.

A virus breaks outs suddenly, downing the world’s cities in a blink, and turning the human population into some very aggressive and agile flesh-eating zombies – it can take a mere 12 seconds for someone to cross over. Some survive initially and find refuge, including a savvy and well-connected former United Nations investigator and his family. He and others desperately seek the cause of the outbreak while trying to not shoot themselves in the foot, so to speak; we just can’t help ourselves at times.

That’s why director Marc Forster’s mostly gore-free zombie flick, made up of two-thirds thrilling action-adventure and one part mediocre suspense, is simultaneously silly and honest. At least five instances of human stupidity – hubris, carelessness, selfishness, what have you – turn the film and alter the storyline. Sometimes the acts only slightly change the course of events, but in one case it causes a monumental problem.

It would seem true to life, so it’s forgiven. It’s an entertaining piece of summer fare, peppered with a few smart laughs but always serious and dire. At its best it evokes Steven Soderbergh’s Contagion (a global outbreak is made small by following a sympathetic figure), and at its worst, Roland Emmerich’s 2012 (there are a lot of close calls and epic escapes of inane proportions).

Still, Forster wastes no time in getting to the tension. After breakfast, where we get to know a family made up of two adorable daughters and two attractive parents, a drive in the car suddenly turns into startling chaos. It is perhaps the most authentically distressing scene, one fueled by uncertainty and fear as the streets are littered with fleeing humans and vicious attackers, with explosions erupting and cars toppled.

It’s a contrast to later scenes when the characters (and audience) know with what they are dealing and when instead of unprepared families on the line, it is soldiers and a better-armed Lane risking their necks.  Lane and company take to a rain-soaked South Korean army base at night, later heading to Jerusalem where both human ingenuity and ineptitude await, the latter of which gives way to a most impressive zombie raid.

The big is made small in a finale that slows to a crawl as Forster changes course. Endings seem especially hard to conceive of lately, and this is fine if not wanting. However, some of what transpires would be tense if not for some head-scratching human actions.