It is seven a.m. on a spring morning in Jerusalem. Eighteen-year-old Dima trudges through the mud to college and reflects on many things, including her forthcoming marriage to her cousin Faris.

Seventeen-year-old Myriam skips school to sit on the tree-lined hill overlooking the city and think about her friend Michael, whose death she still mourns. And Dima's and Myriam's families - one Palestinian, one Israeli - go about their ordinary, separate lives; for today is like every other day.

Yet in seven hours' time, everything will have changed.

For ever.