April 2011 was the most violent month of tornados on record, and the deadliest in modern times. The ‘super outbreak’ of April 26-27 alone involved more than a hundred separate twisters, killing over 300 people and cutting a swath of destruction across the south. Using dozens of amateur and professional sources, Witness tells the story of this once-in-a-century event, as captured by those who lived through it.