It's a recent book by a female author. During a family gathering some members of the family (brother, his wife and some children, I think) disappear for a few hours, then reappear without an explanation. Everyone is mystified and intrigued. I seem to remember it all turned out to have something to do with the brother's wife not wanting to look after her disabled sister in some roundabout way, but I might be getting mixed up with another story...
I can't remember the title or author for the life of me and it is driving me nuts!!