The previous commenter stated that he/she didn't understand what happened. Here's my take on it - the young missionary and his wife arrive to help the older missionary in his duties. The older missionary is married to a bossy nag, and when he sees the young missionary wife, he is smitten. The young missionary wife is not happy with the lifestyle her husband has chosen and drops some hints to the older missionary. He praises her beauty and says he would treasure her. The older missionary knows his wife would be jealous of the attention he is paying the young wife, and basically sets her up to try and murder the young wife. I believe he fakes being asleep while the old missionary wife sneaks into the young wife's bedroom, and the young wife is ready for the attack, thus the the old naggy wife is killed instead. The old missionary and the young wife then bury the old wife; the old missionary tells his native assistant that the young wife died of cholera, and that he must get his wife away from the disease. The assistant doesn't know that the young wife is the one leaving, as she's wearing bug-proof clothing including covering her face. When the young missionary returns from a trip, he's told that his wife died, and that the old missionary and old wife have left. The young missionary presses the assistant to tell him where his wife's grave is, and when he finally finds it, and digs it up, I believe he sees that the body was stabbed, and probably the face was unrecognizable. So, he thinks the old missionary and/or his wife have killed the young wife, and he hurries to the boat dock to exact revenge. He shoots the old missionary, and what he thinks is the old wife, only to find he has shot and killed his own wife, after lifting her veil. He didn't know that his young wife faked her death and was running away with the old missionary. That's what I got out of it...
