Atom Egoyan first read a news article about a Jordanian man who sent his pregnant Irish girlfriend on an El Al flight with a bomb in her luggage, without her knowledge, in 1986. He encountered the story again in 2006 which made him decide that there was ripe material here for a film about the extremism of terrorism and parental legacies.
The character of Tom was originally written as being older. Scott Speedman had read the script in Los Angeles and insisted on meeting with Atom Egoyan. When the director met Speedman, he immediately revised his preconceptions about Tom's age and made him younger.