She apparates to Hogsmead and marches to the Hog's Head.
Aberforth doesn't question her knowledge of the secret passage, but does gruffly compare her to Albus - a chessmaster making plays.
She hates that she knows he's right.
When she steps into the Room she takes control knowing that, soon, they'll forget who issued the orders.
"Harry is on his way...War is here."
By the time the trio arrive - Cedric in tow - she has evacuated most third years and below.
She knows it's not enough.
But Harry needs the room.
So...she joins the fight.