When she used to travel with the Doctor, Martha kept a few spare TARDIS keys, just in case. She doesn't have the one that got made into a perception filter - the Doctor has that - but there's one in a drawer somewhere in her flat. The thing is, that's in London, and not exactly easily accessible here in Cardiff, unless she wants an hours long train ride there and back just to get a key.

Jack said that when he knocked, the Doctor turned on loud music and ignored him until he went away, so knocking is probably not the way to go. Luckily, Martha knows where the Doctor keeps his spare key.

Unluckily, she's not sure she can reach it.

Martha considers the police box sign, hands on her hips. Glowers at it, rather, like it's just insulted her mum or something. There's a little hidden compartment, just over the P, just big enough for a key to fit in there. Which is reasonable, considering the Doctor doesn't exactly have a doormat to hide it under, but she has to wonder if the Doctor has ever been short enough to realize that might be a problem.

Martha glances around the Plass briefly, but of course there's nothing she could drag over to stand on. That would just be too convenient.

She steps forward and reaches up, hoping maybe she can reach it. Standing on her tiptoes, her fingers brush the top of the sign, but don't quite reach far enough to grab the key. She drops back onto her heels with a sigh, glances around to make sure no one saw that, and turns away to walk back to the tourist information center.

Explaining this to Jack is going to be fun.

Jack reaches up, easily retrieves the key, and hands it to Martha, admirably with only a slight twitch of his lips. Evidently, he got all his mockery out on the way back up.

"Thank you," she says, and then makes a shooing motion with her hands. "Now go."

"You don't want me to come?"

"If we both go in there, it looks like we're ambushing him!"

"Which we are."

"Well. Yes, but more subtly."

Jack raises his hands in surrender and turns away, starting toward the lift. Martha turns to unlock the door, and then freezes. "Jack!" she calls just before he reaches the lift, and he turns back to face her.

Martha smiles sheepishly. "Actually, could you just wait out here? And stand to one side so he can't see you?"

Jack starts back toward her with a quizzical expression. "Sure. Why...?"

"I need you to put the key back when I'm done."