Not much is known about this unspecified incarnation of the Time Lord known as The Doctor.
Travels with John
Quest for the power crystals
The Doctor and John arrived in a cave in-which they found a device with a force-field that required three crystals to disable it. They also found a map and set about retrieving the crystals. (DW: Episode 2) The first crystal was located in a place well guarded by police. (DW: Episode 3) The second crystal was located as part of a child's necklace. (DW: Episode 4) The third crystal was hidden in the mouth of the ruler of an alien colony. After retrieving the three crystals, they returned to the cave, deactivated the force-field and took the wishing stone. Upon its first use, John wished for a female named Lucy. (DW: Episode 5) Afterwards, they encountered the Master. During this encounter, the Doctor's leg got burnt off. (DW: Episode 6)