There's a great story in "Blood Diamond," about the conflict diamonds and the brutal turmoil in Sierra Leone (and the unmentioned Ivory Coast), with civil wars raging, limbs cut off and child soldiers abducted and turned into killing machines. And there are a couple of brilliant performances, by Leonardo DiCaprio and Jennifer Connelly. But writer Charles Leavitt and director Edward Zwick insist on teaching us about it all rather than letting the drama unfold without their supposed help. So every time we are about to get swept up in the film it takes us away to make another didactic point.

Even so, "Blood Diamond" is fascinating and powerful and, mostly, true to life. Blood diamonds are the ones mined under terrible duress by both revolutionary groups and the governments of the West African countries, then sold on the world market to buy more guns or, alternatively, to use as escape wealth for the leaders to take away with them when it's time to leave. In the film Solomon Vandy (Djimon Hounsou) is a village fisherman and his young son Dia goes to school with dreams of becoming a doctor. But the rebels come and take Solomon away to be a slave digging for diamonds. At another they take ten-year-old Dia as well, to be a soldier. Solomon digs up an enormous, hundred-carat pink diamond and hides it, knowing that it could be his only way out.

DiCaprio is Danny Archer, perhaps the last of the proud white Rhodesians before it became Zimbabwe. He fought with the apartheid regime in South Africa against the ANC, and now shows up in Sierra Leone because he's heard about the diamond and wants Solomon to get it for him in exchange for getting his son back. He meets Maddy Bowen (Connelly), a journalist in the mode of Christiane Amanpour, who wants Danny's take on the whole blood diamond world. Danny, though, owes his old South African colonel a debt that can only be paid with the diamond.

That's the setup, and how it all plays out is the burden of the film. DiCaprio has taken a great chance here to play with a workable South African accent, and he gives us a portrait of a real mercenary, resourceful, understated, and completely believable. Connelly is a great choice as his foil, the journalist who knows her way around the world of conflict and death and doesn't take any shit from anyone. We feel the sexy attraction they both have for each other, but it is never allowed to take over the film.

All of which, combined with the overwhelming beauty of Africa (the film was shot in Mozambique and South Africa) should have made for a wrenching, even transformingly powerful film experience as the three play out their own agendas, but then Leavitt and Zwick force the dialogue into banal statements of morality, as though we would never understand what's happening unless we have it repeated for us. And the climax of the film gives us DiCaprio in a John Wayne pose that was a cliché fifty years ago. More even than that, they've tacked on another ending, in London, to make the point again that blood diamonds are a very bad thing. Thanks, but we knew that already.