A Griffindor's Bravery

After the war is lost and Harry, Ron, Ginny, Fred, George, Percy, Charlie, Bill, Flur, McGonagall, Hagrid, Dumbledore, Flitwick, Dean, Seamus, Parvati, Lavender, Colin, Dennis, Trawlany, Oliver Wood, Kingsley, Molly, Arthur, and many others are dead, Hermione is captured and tortured by Bellatrix Lestrange for two and a half years, she remembers a memory Harry removed from her mind. She knew it was important, and he removed it to keep it safe. She knows this is the key to saving them, but she can't figure out what it was.