Weird Problem of Good

Prem Sharma's wedding to Nasreen Sanim collapses when she uncharacteristically bows to her conscience and exits the ceremony. After wandering alone to Middlesbrough town centre, he bumps into Ur¿ula Petulengová, an illegal migrant who manages to convince him she's someone she's not. Warming to her, despite his ordeal, and dimly sensing her true predicament, he invites her to stay with him on a friends-only basis. She accepts.
Fast forward a few months, and all three are beleaguered by a network of women-traffickers who will stop at nothing to expand their empire. If that means torturing Prem to death, and forcing Ursula and Nasreen into sex-slavery, so be it.
Given that their survival depends upon it, can our three protagonists learn to cooperate? Can they do even better, and take the fight to the enemy?
And just what is the 'weird problem of good' anyway?