The Toll by Cherie Priest

In a small swampy Southern town, a young couple comes for their honeymoon but a strange bridge appears out of nowhere and when the husband wakes, his wife has disappeared. Cameron after being abandoned as an infant is being raised by two elderly women who seem to be harmless but he is soon realizing that they are not they claim to be nor is what is going on in the big farmhouse they live in. The town's history contains an urban myth about multiple floods, missing people and a bridge that you can only find some of the time. The out of towner just wants to find his wife and leave town, Cameron wants to find the barmaid who he is madly in love with but is too old for him and the witchy women just want the creature and bridge gone forever. A bit "Billy Goats Gruff" and very spooky, this is one bridge in the weird mist that you do not want to find yourself on.