Joseph Campbell first wrote of the hero’s journey - which he also called the Monomyth - in his book, The Hero With A Thousand Faces.
His basic premise was that every myth and story follows the same steps; and that these steps somehow resonate within us as humans, and we respond to that kind of story.
He identified and categorised those steps for use in screen-writing and story-telling.
Screenwriter Christopher Vogler then simplified this somewhat, in his book The Writer’s Journey. This book is well worth buying and applying, and I very much recommend it. But here, first, is a quick summary of the steps of the hero’s journey. Bear in mind that many of these steps can be interpreted metaphorically, depending on your story.
The Hero's Journey
- Ordinary World
Since the adventure/story is going to take the hero out of his/her (the word hero refers to either gender) normal life into something different, the reader needs to see the ordinary world first, so they can contrast it. (see Start Writing A Novel for more on this).
- The Call to Adventure
This is the first sign that something’s about to change. It's the opportunity to solve an existing problem, or a new problem arriving.
- The Refusal of the Call
The hero might be reluctant and try to get out of the adventure. Or they might be happy to go, but someone else tries to caution them. (This stage isn’t always necessary).
- Meeting the Mentor
The mentor will be exactly that - somebody who helps or advises the hero before he/she goes to the new world, or just as they’ve reached it.
- Crossing the First Threshold
This is the moment when the hero leaves his/her old life and starts on the adventure.
- Tests/challenges, allies and enemies
Obviously since the hero is in a new life/place/situation, he/she is going to encounter plenty of challenges, allies and enemies.
- Approach to inmost cave
The hero comes to the place of his/her greatest danger. It can literally be a cave or a physical place, but it doesn’t have to be.
- The Ordeal
This is the hero’s most dangerous moment. I couldn’t ask for a better example than the awful situation James Bond always finds himself in, fighting for his life.
- The Reward
The hero gains something from the experience, whether it’s a tangible tool which will help with the rest of the adventure, or more understanding.
- The Road Back
The hero is trying to get back to his/her Ordinary World, but there are other challenges here. Maybe the defeated opponents are chasing him/her.
This can be a second life-or-death moment. It’s a final test for the hero. The hero is often transformed by this experience.
- Return with the Elixir
The Elixir is the metaphor for whatever it was the hero sought. He/she is returning triumphant with it.
Now, this is a very quick run through. The Writer’s Journey goes into much more detail (including a good section on archetypal characters such as the mentor, the guardian of the threshold and so on), and as I say, I recommend it thoroughly.