"Fitz," said the Doctor. "Has the light under the cell door gone?"
"No," said Fitz.
"Then the brainchip must have started to malfunction, like I predicted. Visual nerve connections have gone first." He took a deep, panicky breath, reaching out. "Just as long as I can walk..."
"We've got to hack into the lock first! How will you—"
"You'll have to do it."
Fitz looked helplessly at the Doctor. "But I don't know what any of these wires are!"
"Don't worry, I'll talk you through." His voice became curiously serene, even as Fitz was panicking. "First, find the green wire..."