Your heroine has just been kidnapped and your hero is really the only person who can save her.
Why has she been kidnapped and who took her? Why is your hero the only person who can help her? Why is he reluctant? For example, maybe he thinks she’s better off with her kidnappers or maybe he doesn’t think he has what it takes to rescue her and he’s afraid to fail.
Does your hero know your heroine and if so, how does he know her? If he doesn’t know her, what happens when they first meet?