Monday, Aug. 24: A fatal love triangle

It seemed at first like a straighforward crime of passion:  A husband straying, a wife betrayed, a body found in their bedroom. But this story wasn't so simple. For one thing: though the wife was accused, the mistress called police to the scene. And in a final twist, was the motive for murder not passion at all, but something far more more cold-blooded and calculating?

NBC's Josh Mankiewicz reports on what really happened "In the Bedroom." Join us Monday at 10 p.m. ET, 9 p.m. CT for Dateline NBC.