Humankind really sucks sometimes. We fight massive wars, we created global warming and we’re spiteful, hateful, murderous, deceitful and thieving.

You can add another item to that list after seeing “The Cove,” where, in a secluded lagoon near a Japanese fishing town, over 23,000 smart (their intelligence is supposedly on par with humans), self-aware dolphins are killed in the most brutal manner imaginable every single year for no discernible reason.

In his directorial debut, Louie Psihoyos follows the quest of activist Ric O’Barry to expose the dolphin slaughtering practice in the town of Taiji, Japan. Between the months of September and March, fishing boats create a “wall of sound” to confuse the sonar-sensitive dolphins and trap them in a shallow staging area. Here, the most attractive bottlenoses are sold to the theme park industry for dolphin shows at exorbitant prices. The rest are driven to a secret cove and killed. Together, Psihoyos and O’Barry work their connections to assemble an unorthodox team capable of exposing this atrocity.

The movie does an exceptionally thorough job of giving context to the killings by tracing the history of dolphin entertainment and capture. O’Barry in particular has an extremely compelling back story. Once the world’s foremost authority on dolphin training, O’Barry himself actually captured the five dolphins used to play Flipper in the eponymous 1960s television program. The show sparked worldwide dolphin mania (at least at sea-themed amusement parks), and the dolphin capture industry exploded as a result.

O’Barry quit his job after realizing the psychological toll captivity takes on dolphins, thus the documentary has elements of an extremely personal redemption story. Though it is plain to see everyone involved with the operation has a serious conservationist agenda, the pain O’Barry feels from his role in creating the industry and his passion for cleaning up the mess are downright compelling.

For a documentary, this movie has definitive style. In one neat parallel, images from night vision and heat-sensitive cameras are juxtaposed with information about dolphins’ incredibly advanced sonar, giving the impression that the images on the screen are those that dolphins perceive.

Additionally, the styles of the title sequence and transition font as well as the plot structure are consistent with the subject matter. As enjoyable as it is to watch an ensemble cast of environmentalists put together a stealth operation involving movie scenery, freestyle diving and unmarked vans, it’s several times more engaging when the music from “Ocean’s Eleven” is playing in the background. Similar shadings of an espionage caper appear throughout the middle portion of the movie — appropriately enough, because of the secretive nature of the cove and the ever-present plainclothes police assigned to follow O’Barry — and this conceit helps the movie maintain a crisp pace while heightening intrigue.

It’s enough to make you temporarily forget the film’s tragic subject matter. But the payoff to all the recon and misdirection quickly takes a much more serious tone.

When several minutes of bone-chilling footage is presented nearly without comment, the reasons that the group has risked international arrest and bodily harm are instantaneously clear. Happily, the movie has already had some influence. The Associated Press reported on Sept. 10 that the dolphins from this years’ first catch would be set free rather than slaughtered. However, the Taiji fisheries association has continued to resist a comprehensive no-killing policy.

All this is not to say the movie is flawless. For example, the first half of the movie focuses on the superior intelligence of dolphins, a fact viewers are expected to accept through anecdotal evidence. Dolphins are illustrated only as hyper-intelligent, sensitive creatures who anticipate and feel pain just as acutely as we do and whose killing is thus obviously immoral.

By contrast, the second half of the film illustrates the uselessness of dolphin meat for human consumption (due to high mercury content), but this revelation renders much of the first act irrelevant and exposes it as a clear bid for an emotional reaction. It’s a little misleading for a documentary purporting simple exposition to fall back on clich?d save-the-whales pathos.

Global warming didn’t end after “An Inconvenient Truth.” “Sicko” came out in 2007 and our national health care situation is still in limbo. People eat trans fat despite the best efforts of “Super Size Me.” Maybe it’s just too much to expect those things to change as the result of a documentary; each are complicated issues with entrenched conflicting interests. Still, the message of “The Cove” is clear: For the love of God, people, stop killing dolphins.

4 out of 5 stars