One muggy afternoon in June 2010, Don Heathfield and his wife, Ann, were relaxing over a bottle of champagne with their two sons, Tim and Alex, when they heard a loud knocking at the door. The family was celebrating Tim’s 20th birthday at their comfortable home in Cambridge, Massachusetts, after lunch in a restaurant. Tim’s mother went to answer the door, calling out as she did so that some of his friends must have arrived to wish him a happy birthday. Instead she found a group of men dressed in black waiting on the doorstep. Bellowing “FBI”, they barged their...