so when he suddenly vanished without a trace, gavin's sisters wondered why his wife lisa wasn't doing more to find him. overs years forced lisa to reveal and uncover painful things about their marriage.s keith morrison with "dark valley". >> there was a kind of peace here, in her own chosen exile, vast pacific for company. how else to live with what's impossible to understand or forget? what began that sunny afternoon far away in southern california, san fernando valley, early may, 2012. >> something was really wrong, but a lot were wrong than i could imagine. >> reporter: it was the boy who knew at first, knew something was wrong.