More than simple plot hooks or adventure seeds!
A premise is the heart of a story summed up in a single sentence. It should provide a general overview of what happens, without spoiling anything. A good premise contains, explicitly or by implication, four key elements of the story: who the protagonists are, what the goal of the story is, the sorts of obstacles that need to be overcome in order to achieve the story goal, and who the antagonist is.
Each premise provided in this book is more than just a story hook or adventure seed. It is the beginning of a story, your story, that you can flesh out and develop to suit your specific needs. These can be used again and again by varying the details, changing the four key elements, and altering details like locations, themes, and the rewards and complications that stem from whether or not the protagonists can achieve the story goal.
The assumption is that you already have player characters created, if not fully established. For that reason, elements of the premise should be tweaked to suit the abilities and personalities of the protagonists and not the other way around. Suggested character capabilities that could useful in completing the story goal may be listed, but if no protagonist possesses these traits then a supporting character should be inserted to compensate. Likewise, ties to background elements can either be retconned into a protagonist’s history, or given to a supporting character who can either ask for the protagonists’ help, or hire them to pursue the story goal on their behalf, as appropriate.
The story goal is the objective that the protagonists must achieve in order to successfully complete the adventure. It’s how your audience, whether they are readers, viewers, or players, knows that the story is over. The purpose of the story goal in a tabletop roleplaying game is to keep the players focused and their protagonists on the right track. In a simplified 3-act structure, Act 1 will have the protagonists learning about the story goal and deciding to pursue it. Act 2 will present a series of obstacles that need to be overcome in order to accomplish the story goal. Act 3 will have the protagonists facing the final obstacle, defeating the antagonist, achieving the story goal, and earning their rewards.
Achieving the story goal shouldn’t be easy. The protagonists will need to overcome an escalating series of obstacles. These might be linked thematically, or somehow related to the nature of the goal that needs to be achieved. Start with a simple obstacle early in the story, something that plays to the protagonists’ strengths and will be relatively easy to defeat. Then think of the hardest thing possible, pushing the limits of the protagonists’ capabilities, and make that the final obstacle. Flesh out the middle with obstacles that are increasingly more difficult, bridging the journey from beginning to end.
Each antagonist should have a personal goal that they are trying to achieve, as well as a motivation for pursuing that goal. This might place them in opposition to, on into competition with, the protagonists. If the premise fits with an established antagonist that you have used in previous stories, you should use them. Tweak other elements of the premise to fit their personalities and abilities. Otherwise, you can create a new antagonist that suits the particulars of your desired story and overall campaign or series needs.