Available on DVD: “The Hunter”

An ecological thriller about a professional animal killer and loner who discovers a newfound sense of stewardship for the planet — along with a concern for other people — The Hunter is engrossing and thoughtful entertainment. It’s a mystery with a message.

Based on a 1999 novel by Australian writer Julia Leigh, the film stars Willem Dafoe as Martin, an elite hunter who has been hired by a mysterious firm to bag the last remaining example of a Tasmanian tiger, a real-life (though probably extinct) predator that looks like it’s part dog, part cat. Though the firm’s reasons for wanting the animal are murky, they become clearer — and more clearly nefarious — as the mystery unfolds.

Martin doesn’t really care why though. He’s in it for the money.

Martin’s efforts to track the animal are hampered by unseen (and possibly dangerous) enemies: radical environmentalists, or "greenies," who want to save the tiger; local loggers who have somehow mistaken him for one of the greenies; and rival hunters.

Martin, in short, becomes both hunter and hunted.

That’s one part of the story.

The other, more interesting part involves Martin’s relationship with Lucy (Frances O’Connor) — a greenie in whose remote Tasmanian house he has set up camp — and her two children (Morgana Davies and Finn Woodlock). Although it behooves him to remain emotionally uninvolved, Martin can’t help developing feelings for Lucy, whose husband has recently disappeared and is presumed dead. But Lucy’s kids also insinuate themselves into his affections. As Lucy’s loquacious daughter Sass, Davies is a charmer. Woodlock is equally memorable — in a virtually mute performance — as the boy, Bike, a character on whom much of the mystery hinges.

Australian television director Daniel Nettheim tells both stories well, braiding them together into a single thread with a firm hand and evocative visual style. The forests of Tasmania are brought to gorgeous life — as is the tiger, in a few moments of believably executed CGI.

But the film’s neatest trick isn’t getting us to believe in a beast that likely disappeared sometime in the 20th century and that now exists only in taxidermied museum displays and black-and-white video clips.

It’s convincing us of Martin’s transformation from hard-boiled mercenary to almost-family man, precipitated by a tragedy that reveals the true heartlessness of his employer. Dafoe carries off both extremes of Martin’s character with aplomb and psychological depth.

At the core of the movie is the message that the real lonely hunter is the heart.