Rent The Crack in Space

When a repairman accidentally discovers a parallel universe, everyone sees it as an opportunity, whether as a way to ease Earth's overcrowding, set up a personal kingdom, or hide an inconvenient mistress. But when a civilization is found already living there, the people on this side of the crack are sent scrambling to discover their motives. Will these parallel humans come in peace, or are they just as corrupt and ill-intentioned as the people of this world?