After their failure with the polyjuice potion, trying to gain information about the chamber of secrets, they moved onto plan B. They now knew where the entrance to the Slytherin common room is, and the password, so what's stopping them from exploring it further. If they couldn't extract any information from Draco, then perhaps they could find some clues lying around.
Ginny was sitting in the corner listening to Ron and Harry's plan. They never noticed her listening in, as she pretends to write some more in her journal. She wished she could get Harrys attention once and awhile and not be so immature.
They planned to sneak down to the dungeons, after curfew, hide under their invisibility cloak, and sneak in while using their marauder's map. How childish, do they have no imagination?
"That's not going work you know?" Ginny finally piped up, as if she's done it before.
"Stay out of it Ginny, it's non of your business." Ron replied in a disgusted tone.
"Well its true! I mean you're lucky you aren't suspended after what happened to Hermione."
"And how do you know its not going to work?" Ron retorted.
"Being Fred and George's sister has its benefits. First off, what if Snape suspects something and goes to check on the common room. There is only one way out, you'll be trapped."
"She has a point Ron." Harry remarked. "We don't need to get into anymore trouble then we already are."
Ron turned to Ginny and asked "And what, you think you could accompany us on this little adventure?"
"Why not?" she replied.
"Because you're only in first year!" Ron snapped.
"Yah so, you're only in second!" Ginny snapped back.
"Fine! But if you get caught, it's not our fault!"
So they huddled around the table, beginning to devise their plan. Ron will wait at the end of the corridor, to make sure there is no sign of professors with the map. Ginny will wait next to the entrance of the Slytherin house, and hope that Ron doesn't give the signal someone's coming. If he does, then Ginny will send the signal to Harry in the common room to get out and they'll make a run for it. They will then all take three different routes, meeting up in the hallway near the kitchens on a few floors up. From there they will all go back to their common room together.