"What the hell was that?!" the three Donnas shrieked in unison, spinning to face the wooden doors of the TARDIS.
The Doctor followed the immediate gaze of Donna and her dopplegangers, towards the direction of the persistent thudding.
"No idea...let's find out!"
The Doctor bounded toward the doors with his usual enthusiasm and child-like energy. For a 904 year old, he didn't half run fast...
"Some use you are..." Donna muttered darkly, frowning after the blur of brown fabric and blue pinstripes that had just zoomed past her.
As the Doctor reached for the handles of the door a louder crack echoed around the room, reverberating from each coral strut. the Doctor leapt backwards in surprise, pulling his hands from the door handles like they were red hot irons.
"Doctor...what's going on?..." one of Donna's dopplegangers piped up, her voice soft and timid, edged with slight curiosity. The sound of cracking wood muffled his reply, as though the wood of the door was splintering, being ripped away. Thankfully the visual evidence of the intact door reassured them all it was not the case.
Everything fell silent.
"Well..." the Doctor's voice was low and hushed in tone, "...I think it's safe to say, not even the third army of the Costa Regis Galaxy could get through those doors, and believe me they've tried-"
The Doctor was abruptly interrupted by another loud crash from outside the TARDIS.
"You were saying, Spaceman?" Donna quirked an eyebrow, mirrored instantly by her clones, reinforcing the effect. The Doctor shrugged and scratched his chin in what Donna presumed to be a thoughtful manner.