In chapter five of Dumbledore's Army and the Year of Darkness the DA's latest mission is to break into the Headmaster's office and steal the Sword of Gryffindor.
Padma and Parvati would guard one end of the hall, while Susan and Hannah would guard the other and Terry and Michael would guard the middle, right at the foot of the stairs to the Headmaster's office; all while under Disillusionment Charm. Meanwhile Neville, Ginny, Ernie and Luna would climb up the side of the castle (all seven stories) to where the Headmaster's office where they would use a Portable Portal which Ginny and Luna would crawl through and then open the window for Neville and Ernie (because the Portal would only make a small hole since it wasn't meant to go through solid stone). Then they would smash the case and jump through window (using Featherlight Charms on themselves, so they would float softly to the ground) and then Neville, Ginny, and Luna would return the towers (on brooms) and Ernie would head back to his common room, on his way giving the sword to Dobby, who would take it to the Room of Requirement (so Snape couldn't get it back).
Problems started immediately. First, it took them longer to climb then expected, and then, when Neville and Ernie went to pull themselves onto the sixth story ledge it crumbled beneath their weight. Neville caught himself on the way down but Ernie went all the way back to the bottom (thankfully Luna hit him with a Featherlight Charm). Neville ordered Ernie to return to his common room (there wasn't enough time to have him climb all the way back up). Neville then climbed back up to where the girls were waiting (on the seventh story ledge, which they had reinforced). They got in as planned, and smashed the case. But after Luna grabbed it (only Gryffindor's are supposed to hold it) the room changed so that there was no tables or portraits and the window was gone so they went to go out the door and the stairs had changed into hands all trying to grab them. Neville had gotte a ways down but when he heard Ginny scream he stopped to turn around to help and was grabbed. Then Snape arrived and he didn't see them at first (they had put Disillusionment Charms on themselves) and went into the office but then came back out and grabbed them (taking the sword as well).