I THINK the word that you are searching for is PLOT, which is the main events of a play.
"<span> Polish and British cryptologists had already developed alternative methods of recovering the daily keys. "
Just before it, the passage says "the Germans introduced additional rotors and plugs... increase the number of possible combinations".
As this was expected, so the Polish and British "<em>already</em> developed alternative methods"
hope this helps</span>
