9.21am: business as usual on a high street in England.

9.22am: the explosions are heard for miles around, and in the early confusion there is talk of a gas leak, a plane crash, and even terrorism . . .

The people of Heathwick had been preparing for Christmas unaware that many would die, and the rest would be transformed for ever. Travel with them, second-by-second, through the hopes, fears, love, worries, gossip, cruelty, kindness and trivia that dominated their final minute before tragedy struck.

And in the everyday story of an ordinary street, look for clues to what happened, and why.