What lies ahead on the river, who manages to pass it and how does the crowd feel about him?

There are rapids ahead. The rapids are considered to be quite dangerous and last for five miles. There are box canyons, whirlpools and eddies to be traversed, and no one in his right mind would do it. No one, that is, except Jack London. The crowd is in awe as London and his crew make it over the rapids.