What trouble did the children get into when they traveled down the gorge?

At one point in the story, the four Pevensie children, along with little Trumpkin, are making their way to join good Prince Caspian. They decide that the best way to reach their destination will be to climb down a gorge and follow the river. But Lucy, who has remarkable powers of intuition, is not so sure.
Just as the group's about to descend down the gorge, Lucy looks up and sees Aslan, silently beckoning her to follow a path up the mountain instead of down. But as Lucy is the only one who's seen Aslan, no one else thinks this would be a good idea. It just doesn't make sense, not least because no one can see where the mountain path actually leads. So the decision is made to stick to the original plan.
However, when the party descends to the bottom of the gorge they walk straight into a trap. Immediately, they're attacked by a detachment of King Miraz's archers, who proceed to rain a hail of arrows down upon them. Trumpkin and the children have no choice but to run for their lives and scramble back to where they came from. Lucy's intuition was right once again.