“Nope,not in there,” the Doctor said slamming the cabinet shut. Being unsuccessful in his quest for the full fuel cell, he had managed to turn up an impressive collection of gadgets that he had either lost or forgotten about. “What's this?” he mused digging into yet another corner of the Tardis. “Oh yeah, my set of frictionless pulleys. Yes, and here are my ropes of negligible mass,” he said pushing them out of the way.

The Doctor gets down on one knee to continue his search, then slowly spins to sit with his back against the wall. Unaware of the growing seriousness of Donna's plight, he closes his eyes and exhales.

“Let's see,” he said, starting his search anew. “When I ran in, I tripped right there,” fixing his gaze on the deck near the console,“and then I fell backwards.” The bruise on his back throbs in agreement.

He scans the deck from his point of impact all the way to the rear wall, and could see no sign of the cylinder. As Donna is persuading her captors, the Doctor is crawling along the wall on all fours. Looking under cabinets, behind structural members, anywhere and everywhere, yet the evasive fuel cell still keeps it's secret.

“Oh my... Aggie and Kim wouldn't approve at all,” he muttered as his best efforts produce only dust bunnies and one lone, dirty, sweat sock. As the wall clangs down trapping Donna with the Superiors, the Doctor rolls over flat on his back and looks up. “Ah ha!” he shouts, a huge smile suddenly appearing on his face, “Now I've got you!”

In all the commotion of the locomotive incident, the cylinder had somehow become lodged in one of the buttress-like beams that radiate out from the top of the Tardis. With a flick of his wrist, and the sonic screwdriver is in his hand. A blue light and hum followed by a click and a slap finds the fuel cell safely in the Doctor's free hand.

As Donna is knocked down the chute, the Doctor enters the Chirgolian control room.

“What d'ya think of that,” he asked with a faltering smile. Somehow there has been a change,almost imperceptible, in the Chirgolian's behavior. The regular rhythm and flow of their motions and tasks were sped up somehow appearing to the Doctor as almost desperate.

The engineer takes the fuel cell and deposits it into a tray in the wall that silently slides closed after it.

“Thank you,” the computer translates for the being, “our engines will be ready in two minutes.”

“So, where's Donna? You know, my companion.” the Doctor inquires.

“The one you call Donna is our Savior.” the engineer said. “She is no longer among us.”

“Whaddya mean savior?” the Doctor asks bluntly furrowing his brow. “What have you done with her?”

“She chose to selflessly give her life in a diversionary tactic that will allow us to escape the Superiors.” the translator drones. “We shall finally be free.” Waving its' hands over the lights on its' control panel, the engineer said, “one minute until departure.”

“How are you getting free then?”

The Chrigolian turns toward the Doctor in what could almost pass for annoyance, “we can separate the control compartment from ours in case of emergency. The momentum from the separation charges should send the Superiors clear of whatever danger we may be facing while we will be doomed.

“The Superiors monitor the circuits and can abort in case there is no emergency. Now, thanks to Donna, the Superiors are preoccupied. Separation will occur in one point five six minutes.”

“Can you at least tell me where she is?”

“The savior is currently in the maze of passages under the control cabin. There are ten Superiors closing in on her location. We must separate soon, or we will lose the chance. Begin departure sequence.”

The Doctor, torn in a highly unusual fit of indecision, feels like his feet are glued to the floor. If he started now, he stood a small chance of getting to Donna before the separation charges go off, but then they would be stuck in the Null until their universe started or they died. Or, he could get to the Tardis and look for her as the two ships phased through each other on their way back to normal time. Only then, all he could do is watch as a phantom Donna whisked by. If only there was some way to catch her as they pass.

With that thought, the Doctors' feet find a will of their own and sprint him back towards the Tardis. Determination burning in his eyes and talking to himself and the Tardis, the Doctor begins his usual dance around the controls.