''It was a dark and stormy night.."

Figure out a way to get: four people, across a narrow footbridge, over a steep river canyon, in the dark, with only one flashlight, before the flashlight battery runs out, which will happen in exactly 17 minutes. There are, naturally, a few small conditions.
a. No more than two people can be on the bridge at a time. Anyone on the bridge has to be with the flashlight (it's dark, remember).
b. The four people, named, creatively, A,B, C and D, take respectively 10, 5, 2 and 1 minutes to amble (or, in the case of D, hop like a bunny) across the bridge.

HINT