'MARCO POLO' - DAY 2: 'THE SINGING SANDS'...

The TARDIS, now en route through the Gobi Desert, in a sequence filmed at Ealing Studios for The Singing Sands.

Ready to begin his plan in poisoning the water of Marco Polo's travelling caravan and crew on its long and adventures -packed journey to Kublai Khan in Cathay, Mongol warrior Tegana, heading out to see his band of warriors waiting for him in the desert, is followed by a travel frustrated Susan and her new friend in the lovely Ping-Cho (Zienia Merton), reluctant to be wed to an elderly statesman in a specially arranged marriage which she seemingly has no choice but to honour. Soon enough though, the two are caught in the environmental dangers that the infamous Gobi Desert brings, of strange noises, ethereal hallucinations and sandstorms, that threaten their lives. The Doctor (angry that they must travel to Cathay, yet using the time to repair the TARDIS), Ian and Barbara are vulnerable and powerless to save them. Thankfully, they are rescued by Tegana, who brings them safely back to the travelling party, but they are wary of the warrior and suspect further dangers. Heading out ahead to a desert oasis, Tegana solidifies plans for his warriors to attack Polo and his expedition before they can reach the valuable supply to replenish after their prior supplies had been sabotaged by bandits.

Selected images by Barry Newbery and Don Smith/Radio Times/BBC Studios

Trapped in the eerie wastes of the Gobi desert, Susan and Ping Cho are ultimately rescued by Tegana, the figure whom they were previously following away from the camp.

Polo's travelling camp comes to a stop as the discover their water has been poisoned by mystery bandits.

Posed publicity image, likely taken at Ealing Studios.

Ian confers with Ping Cho in another publicity image.

On set photos of Zienia Merton as Ping-Cho by set designer Barry Newbery.

Pretending to scout for the group, Tegana gets to the oasis and goads Marco as their water supply runs out. "Here's water, Marco Polo. Come for it." he says, deliberately pouring it onto the ground, as the second episode concludes.

Using a unique condensation build-up in the TARDIS, the Doctor is ultimately able to provide water that will save everybody's lives in the camp, though not before Polo angrily interrogates him, accusing the Doctor of keeping the water for himself

Marco fails to believe in Ian and Barbara's suspicions about Tegana, especially as the warlord rescued Susan and Ping Cho.

Marco Polo is not convinced of their accusations against Tegana.

Barbara secretly vows to keep an eye on Tegana.

The journey must continue, of which a scene in the episode The Wall of Lies of our heroes once more voicing their suspicions about Tegana was filmed but ultimately cut.