Thunder rolled over the dunes and the wind picked up, swirling the dust, taking it into the storm. The Master adjusted his face mask, trudged on.
The first drops of rain disappeared into the sand without noticeable effect, swallowed by the thirsty land. But the rain continued, hard and heavy, until the sand was damp underfoot and the Master was wiping sheets of water from his goggles.
The sky flashed, and the Master paused, waiting. One second, two, three-
Thunder rolled over the dunes, louder than before.
Less than a kilometer, and getting closer. The Master smiled and took another step forward.
The lightning on the horizon became lightning in the near distance, became lightning on the dune ahead. The Master stopped walking and let the storm come to him.
He felt giddy with the power of it. A storm in the Sahara, rare and beautiful, rain called by his machine, lashed to his purposes. The locals would be talking about this day for years, for generations. The Master would visit one of their towns of cities, a century hence, and there would be weather researchers eager to tell him about the great storm of '27.
There was a figure coming up and over a dune, umbrella pushing against the driving wind.
Lightning struck a few hundred meters away. The clap of thunder was near-simultaneous, deafening unless you were wearing a pair of selective noise-canceling headphones. The Master patted the devices fitted over his ears, grinned as the figure with the umbrella flinched from the noise.
Another strike, another, closer, closer, again, more, nearly there-
The figure with the umbrella was pushing the Master the ground.
"Get off me," snarled the Master.
"What?" the man shouted over the storm. He shook his head, pointed to his ears. "I can't hear you!"
He was a small man, with dark hair and a serious cast to his face. He was wearing an exceptionally ugly jumper, covered in question marks. He was a stranger, and entirely too familiar.
"Let me go." The Master shoved at the Doctor.
"Stay down!" shouted the Doctor. "Don't make yourself a target!"
"We're hardly tall enough to suffer any additional risk from standing upright," said the Master. He squirmed again, and then gave up. "And you call yourself a scientist."
The Doctor smiled, uncomprehending and implacable. The Master waited, watching the lightning touch the ground around them, then in the distance, then flash in the horizon.
The rain drizzled and dripped to a halt.
The Doctor stood up and shook off his umbrella. "What on Earth was all that about?"
"I needed fulgurites." The Master's voice came out muffled, and he stripped off his mask to assist the Doctor's recovering hearing. "It is imperative that I have fulgurites made from the unique composition of Saharan sand. By directing my ingenious atmospheric emulator to-"
"Oh," said the Doctor. "One of your schemes." He sounded indulgent and amused and more than a little nostalgic, and the Master's mouth closed with an audible click of his teeth.
"No harm done," continued the Doctor. "Yet. I'll leave you to it, shall I?"
"Please," said the Master. He wasn't sure what he meant by that, but the Doctor turned away, strolling through the sand.
Perhaps he would become lost there, in the desert, until an explorer found an umbrella and a jumper and wondered who would bring such things to the Sahara. But more probably, the Doctor would find his way easily enough.
The Master watched him go until the Doctor was just a figure on the dunes again. He took a few steps after him then, shoes scuffing in the hastily drying sand. His shoes hit something hard - a fulgurite.
The Master bent down and pulled tools from his pockets, excavating the long tube created by the lightning striking the sand, heat crystallizing it around the bolt.
He needed four more for the astraphobia machine. The Master kicked through some more sand and didn't look up when the sound of a TARDIS dematerializing rolled over the dunes.