The Overtoun Bridge is an arch bridge located near Milton, Dumbarton, Scotland, which was built in 1859. It has become famous for the number of unexplained instances in which dogs have, apparently, committed suicide by leaping off it. The incidents were first recorded around the 1950s or 1960s, when it was noticed that dogs - usually the long-nosed variety, like Collies - would suddenly and unexpectedly leap off the bridge and fall fifty feet, to their deaths. In some cases, however, the dogs would survive, recuperate, and then leap off the bridge again. What makes this tragic mystery even more mysterious is that many of the dogs that jump from Overton Bridge jump from the same side and from almost the same spot: between the final two parapets on the right-hand side of the bridge.

Some believe that the bridge is haunted. In 1994, a man threw his baby son off the bridge, claiming that it was the anti-Christ. Later, the man attempted suicide there as well. Was Overtoun Bridge responsible for this tragic event? Some believe that Overtoun Bridge is a "thin place", where the barrier between the world of the living and the world of the dead meet, and sometimes cross over.