A horse’s trail instinct can fail, plunging rider and animal through lake ice.

Evidence

But reaching a wild place, I lost it, and still cantered on, trusting to the pony’s sagacity. It failed for once, for she took me on a lake and we fell through the ice into the water, 100 yards from land, and had a hard fight back again. — Isabella L. Bird, A Lady’s Life in the Rocky Mountains, 254

Categorization

• STORYSTEM: A heroine who survives because she trusts her animal, until the one time the animal betrays her — a survival story turn set up and subverted in two sentences.