Brian Horiuchi's unsettling end-of-the-world tale, PARTS PER BILLION, goes straight to Blu-ray

There are pretty much two kinds of end-of-the-world movies. One type is faux, since the world contin-ues, as in the worthwhile Deep Impact or the piss-poor Armageddon. The other version is not afraid to give us the real thing, though this kind of film doesn't come along all that often -- and is never of the blockbuster variety (the hoi polloi demands feel-good). The best of the actual end-of-the-world lot would be Don Mc Kellar's Last Night from 1998, but 2012 brought us another fine example in David Mackenzie's Perfect Sense. Now there's a new one to add to this brief list: PARTS PER BILLION by Brian Horiuchi (below), his first film as writer/director.

While not nearly up to the level of the other two films on my short list, Parts Per Billion is good enough to qualify as a quality product. It's well written, directed and especially acted by the eight excellent performers who play the three couples, the sister and the best friend who comprise the fine ensemble. Mr. Horiuchi, shown at right, takes our current and ever widening revolutions, wars and general anarchy in the mid-east and leaps off from the chemical warfare supposedly used of late by Syria, and from this sort of behavior extrapolates a new kind of pathogen released into the air via chemical warfare. Airborne, it is soon wiping out entire populations. Once it crosses the Atlantic, goodbye USA.

Parts Per Billion concentrates on just three couples, one very young (Teresa Palmer and Penn Badgley, above, right); one approaching middle age (Rosario Dawson and Josh Hartnett, above, center), and one old (Gena Rowlands and Frank Langella, above, left); the Badgley's character's sister (Alexis Bledel, below, who doubles as nurse to Langella and Rowlands); and the Hartnett's character's best friend (the excellent Hill Harper).

Horiuchi tends to bury his exposition well enough so that it tends to pop out only when his characters might actually be talking about that particular subject. He also uses flashbacks judiciously to fill us in on how these people come to be in the position they now find themselves.

The three couples are deeply in love, though not, it seems without having had some bumps along the way. The true beauty of this film is how we come to share their love and believe in it. "What are the important things?" one character asks during the course of the film. Parts Per Billion forces this question upon us time and again in scenes that include Hartnett, a young boy and the boy's father in the park; Badgley and Palmer in a truly lovely proposal scene; and Langella facing down his past behavior and terrible decisions with grit and grace.

Horiuchi's writing is better than this genre usually offers: smart but unshowy and always about things. "This is how wars start," notes one character, " because of the different ways people keep stuff in their cupboards!" When you actually see this moment, that line seems both amusing and sensible.

The filmmaker does not back away from the darkest side of things, either. He spares us the blood and gore but takes us to the brink, allowing us to view (or hear) as some of the characters meet their demise. There's also humour along the way, as well as music, lovemaking and food. As we see our civilization closing down via these eight characters, it becomes clear that Mr Horiuchi has given us an end-of-the-world movie that can actually bear the weight of its subject.

Parts Per Billion -- from Millennium Entertainment and running 102 minutes -- hits the street on DVD and Blu-ray tomorrow, Tuesday June 3 -- for sale or rental. Apparently Netflix hasn't even ordered the film yet (you can "save" it to your queue), but Amazon has it on disc and streaming, the latter via its Instant Video.