The movie is basically about the bystander effect. The protagonist protects two children from a bearded guy (killer?) who in the climax of the movie chases them through a (corn/wheat) field. They try to hide but the balloon, that one of the children holds in their hand) reveals their position. The bad guy is killed when he stands in a puddle and the protagonist puts a life wire in it. During all that a couple of people show up who wak side by side through the field to where the bad guy and the protagonist are and simply watch them while doing nothing.
Later the protagonist explains, that some time in the past she witnessed a crime but did nothing to help the victim (didn’t intervene, didn’t called for help or the police). So the ´when she was saving the children she basically atoned for her sins. Her name might have been something like Maddie, Maggie or something else with an M.
Maybe I’m confusing two movies, but I think in the beginning they discover some kind of tomb or chapel underground and seal it shut in the end.
The film might have been french or american.
It was probably released between 1980 and 1999.