Mis-step

One step may shape a character and destiny. If it be a right step, the character and destiny will be rightly shaped. If a wrong step, a mis-step, then the character and destiny will be wrongly shaped.[…] Only one mis-step! What is it? “Why, I only gave way to a little ill-temper,” but see the result! The children observed it. Children are sharp-eyed. They are close watchers. They are quick to mark the mis-step, and they have tenacious memories.

Source: wiktionary

Unable to see, they lost their bearings in the dark. The wind edged them to the lip of a 7,000ft drop down the Kangshung Face. “One mis-step here and it was a one-way ticket to Tibet,” Fox said.

Source: wiktionary