Lost on Venus — Edgar Rice Burroughs

In the Room Of the Seven Doors, Carson Napier faced the choice of his life. Six doors led to terrible deaths -- the seventh was the door of life. But for him, this door too would lead only to the new dangers of a planet whose beasts were more frightful than those of his native Earth.

But Carson sought the rescue of the planet's fairest princess, and even though he stepped from one danger to meet an-other, he was determined to make good an Earthman's pledge.