"One startling element is the sheer number of sexual predators in the area at the time," the trailer for the documentary narrates. Although the town where the McCanns were staying was a resort popular with European tourists like them, there were also a significant number of convicted predators in the area just around the resort.
The Telegraph also reports similar information: that there had been an unusually high number of assaults on young girls in the area.
"Police identified nine sexual assaults and three 'near misses' on British girls aged between six to 12 in the three years before Madeleine went missing. In one case from 2005, a ten-year-old girl was assaulted in an apartment Praia da Luz, close to the spot from where Madeleine vanished," the article reported. Additionally, The Guardian reported that the police pursued this possibility as well.
"Metropolitan police in Britain appealed for information on a total of 12 incidents in which an intruder entered holiday accommodation in three resort areas including one where Madeleine, then three, went missing in May 2007. Four of these cases, between 2004 and 2006, involved assaults on girls aged seven to 10 and one involved two children, according to Scotland Yard."
This information could suggest that Madeleine was kidnapped by a local predator, perhaps one who had spotted her with her family earlier in their stay.