Deductive storylines use deductive logic at the top level
A deductive argument relies upon all three top level supports being dependent upon each other and together leading you to a conclusion that cannot be disproved.
Deductive arguments begin with a statement (major premise), which is followed by a comment on the statement (minor premise), which leads to an unavoidable conclusion which we call either a recommendation or an implication.
The key is to make sure that the connections between the three elements are tightly linked. For example, the comment must comment on the statement, not on something loosely related to the statement. The implication must be the only logical conclusion if you combine the statement and the comment. If any other outcome is possible, you need to refine your logic.