Chasing through the tunnel, the enemy somewhere, sensing without seeing... there!
Wrapping around the monster, struggling as they tear into each other. Tired but unable to give up, he gets a burst of energy and the foe collapses.
That could be two fighters in a darkened city or a white blood cell in a vein going after a virus.
Keeping some things unknown either to yourself, to the audience, or to other characters in the tale creates drama. Tension between characters is drama--one wants one thing, another wants something different or the same thing at another time, or no action at all.
It's all about asking questions and asking more questions. The eternal 'what ifs' that drives the character drives the reader too.
James Michener has a tendency to start his books from the first amoeba struggling in the primordial stew: ala Hawaii, Alaska, Chesapeake, Iberia, then he tells of the epic struggle of mountain chains and river meanderings.
By the time some caveman is sucking his finger from cutting himself with a flint knife it's like--with the geological upheavals and titanic storms, what difference can one little Neanderthal make?
Michener's a good storyteller but he's formulaic. I stopped reading his stuff in my teens because it was always the same beginning and end: Let there be light, separating the waters from the earth, ooze becomes sentient, a two-legged pre-man bops another and climbs the evolutionary ladder. A bunch of character sketches later, cities and civilizations rise and fall, then today we have a thriving metropolis and the chosen family struggling with itself and the world to stay in one peace.
Of course as the trite saying goes, one person can make a difference--but we need to add the influence of others who base their actions on ones who came before, the vagaries of weather, catastrophic epidemics, the ability of those in power to force change into the wrong hands/wrong hearts.
Drama keeps us going, the struggle for everything or anything can be the pull for the audience to keep coming back.
The old Perils of Pauline had early movie goers more interested in the serials than in the features.
Keep the reader asking, 'What's going to happen next' means that they care, and that's what keeps the writer going.