The “B” Story Rides to the Rescue of the “A” Story
We touched briefly in last week’s post upon the idea that the “B” story “rides to the rescue” of the “A” story, usually at the start of Act Three.
Let’s examine this principle in more detail.

Faye Dunaway and Robert Redford in “Three Days of the Condor”
If the “A” story is the primary tale, i.e., the narrative in the foreground, then the “B” story is often the love story—that is, a secondary narrative that runs parallel to the primary story and intertwines with it as the greater tale unfolds.
In Three Days of the Condor for example (and its latter-day clone, The Bourne Identity), the “A” story is the tale of the man on the run—Robert Redford in Condor, Matt Damon in Bourne. The big narrative question is “Will the hero unravel the mystery and save himself before the Secret Nefarious Forces pursuing him catch up and kill him?”
That’s the “A” story.
The “B” story is the romance that develops along the way as each protagonist (Redford in New York City and Damon all over Europe) kidnaps or recruits a woman off the street and, despite or perhaps because of his other troubles, becomes romantically involved with her.
In both movies, “A” and “B” stories intertwine as the female lead (Faye Dunaway in Condor, Franka Potente in Bourne) becomes swept up in the male hero’s drama and not only comes to care for him emotionally, but becomes an active partner and accomplice in his flight/adventure.
In both stories, there’s an early scene where the female comes emotionally unpeeled when the hero is violently attacked out of nowhere by a mysterious and obviously highly-trained antagonist who’s trying to murder him—and the protagonist, after successfully defending himself, compels his shaken female abductee/recruit to “snap out of it” and “get it together.” Both ladies do.
Not long after, in both films, hero and love interest literally become lovers.
Right after that, again in both movies, a scene unspools in which the female, now acting as the hero’s willing partner, enters the environment of the villain (in Bourne, a hotel in Paris; in Condor, the New York WTC offices of the CIA) to “recon the area” in preparation for the hero entering on his own.
We’re coming now to the All Is Lost moment.

Matt Damon and Franka Potente in “The Bourne Identity”
This is the point in the story, usually just before the Act Two curtain, when the hero finds himself ultimately alone. He has learned enough of the story’s secrets to know he must now enter the lair of the villain and face this devil down or die.
At this point, in both Condor and Bourne, the hero sends the female away, to protect her. (I can think of other stories—The Terminator, Avatar—where the love interest stays and fights alongside the hero.)
The key point, however, is that the love interest, whether male or female, has by his or her love, assistance, wise counsel, and belief in the hero, armed him or her with confidence and prepared him or her for the ultimate clash with the villain in the climax.
The classic fusion of A and B [writes Blake Snyder in Save the Cat!] is the hero getting the clue from “the girl” that makes him realize how to solve both—beating the bad guys andwinning the heart of his beloved.
In both Condor and Bourne, the hero wishes he could stay with the “B” story love interest. Both Redford and Damon send their lovers away reluctantly. The lovers, for their part, don’t particularly want to go either. They resist. In both stories, we sense, the lovers will never forget these men in whose company they have shared such dangers and with whom they have grown so close.
At the same time each hero knows (though he may not articulate this overtly) that he has been strengthened and prepared by the passage he has undergone with his unexpected lover in the “B” story and by her equally unexpected faith in him and belief in him. He now has the strength to “do what must be done” in the climax of the “A” story.
The “B” story has ridden to the rescue of the “A” story.