What terrifies in the terrorism arrests announced yesterday in Ottawa is that the Islamists’ call to mass murder, if the accusation is true, was accepted by a McGill University-trained medical doctor who loves hockey and sang on Canadian Idol. Even those individuals who seem to be, and may in fact be, well integrated into their communities, may not be immune to the lure of jihad. This is not new to other parts of the world, notably Britain, but it is a shock for Canada, an open, integrated society that likes to think its openness protects against violence and radicalism of all kinds.