This Friday, May 15: Watch Dateline at a special time, 8 p.m. ET/7 p.m. CT

Sometimes it's hard to tell  exactly what goes on in a marriage, even in those that seem happy and successful. The Cordes couple was like a lot of others you might know: solid on the outside, but with a deep crack running beneath the surface.

Maybe that was easier to ignore, after they bought a house on an island in the sun. Easier to ignore, until the night the wife disappeared. Join NBC's Dennis Murphy for "The Party's Over."