Zoro was captured by the marines. Luffy and the others weren't worried, well they didn't show it. But they plan to get Zoro back no matter what it takes.

You, who knows the entrances and exits of the impel down decided to help them.

You gave them a map and told them the plan. And of course, Luffy went in before you could speak.

After you all splitted up. You were the first to find Zoro, sleeping in his cell comfortably. The others aren't here yet.