1997... and a lone exile arrives on Earth, years later than planned.
On the eve of the Handover, an advanced Chinese stealth bomber crashes in the hills above Hong Kong. The discredited United Nations Intelligence Taskforce has just 24 hours to steal the technology, rescue the passenger and flee to international waters.
Down by the harbour, there’s big trouble in Little England -- a bar owned by an old soldier who simply wants to forget the past. But an ancient evil is stirring in a place of peace.
The Doctor finds a world on the brink of terror. A world that has lived without him for years. A world that is frighteningly like our own...
After being put on trial by the time lords, The Doctor was intended to be exiled to 1970's England, but instead, he landed in 1990's Hong Kong, on the night of the handover to communist control.
Finding his old friend, the Brigadier, he found out the world had changed due to him never coming to earth since the 1970s. Subsequently,the U.N.I.T. project had failed, and the Brigadier had been kicked out of U.N.I.T., due to failing to stop various disasters. As the two talk, an invisible plane crashes into the nearby mountain.
The Doctor and the Brigadier approach the mountain, looking for Ling, one of Alastair's employees. Ling and Adam discover that the crashed plane belongs to the communists. They rescue the pilot, but he is heavily wounded. The Brigadier and the Doctor then arrive, and the Doctor attends to the pilot's wounds.
U.N.I.T. then arrive, much to the Brigadier's chagrin, led by Colonel Brimmicombe-Wood. Brimmicombe-Wood seals off the area, and takes the pilot in for questioning. A local Buddhist monastery is used as U.N.I.T. field headquarters.
Adam is still trying to the find the other passenger, but is killed by the mysterious Ke Le...
Brimmicombe-Wood interrogates the Doctor and the Brigadier, and chastises the Brigadier for his failures, criticizing him for failing to stop the Probe 7 disaster, and the plastic purges, amongst other invasions.
In the monastery, the Brigadier visits the abbot, who tells him about 'the soul jar' of which the monks have chanted, non-stop for 150 years. Meanwhile, The Doctor translates the pilot's speech, saying that Ke Le told him to crash the plane, and threatened to kill him. Ke Le was the head of the Ke Le division, a Chinese group of ex-convicts who go on government suicide missions, and are presumably mind-controlled. The pilot mentions something that could 'steal souls'. The Brigadier tells the Doctor about the soul jar. Ling recalls the passenger 'changing'. The Doctor works out who the passenger really was. Meanwhile in the woods, Ke Le, (actually the Master) kills Adam.
Adam's body is taken back to the monastery, as the soldiers assume he is Ke Le. The Master hands himself in. Upon entering the monastery, the Master threatens the abbot, and makes him give the Master the soul jar. The Master reveals the soul jar actually contains a mind-control parasite. The abbot is killed by the Master, and the Doctor, the Brigadier and Brimmicombe Wood are captured by mind-controlled U.N.I.T. guards.
The Doctor is released by the Master, who tells him that his new plan has 'noble intentions'. He intends to rule the world to cause world peace. The Master reveals that he has been trapped on earth since the 1970s, and chastises the Doctor for never returning to earth. The Master rants about how he has had to live through the wars, and the panics, and the shortages, while causing 'minor diversions' to hopefully attract the Doctor's attention. He plans to use a Chinese military bomb testing to release the parasites to control the world. The Doctor agrees to make a deal with the Master, and Brimmicombe-Wood and the Brigadier are released.
They lead the mind-controlled monks and soldiers down to the waterside, and the Master agrees to stop the parasites in exchange for the TARDIS. He gives the Doctor the soul jar in exchange for the keys to the TARDIS.
The Doctor and The Brigadier take the TARDIS to Mongolia and throw the soul jar into the bomb testing site destroying it. Meanwhile, back in Hong Kong, the Master was tricked into thinking the TARDIS was disguised as the Little England pub. The Ke Le divisions approach above in helicopters after the handover is complete. Brimmicombe-Wood prepares to leave, and the Master begs him to take him with him. Wood refuses, put the Master reveals that the Ke Le divisions will go mad, now that the parasites are dead. Thousands are killed by the helcopter's gunfire.
Later, the Doctor manages to free the TARDIS, and the Brigadier accepts. They both leave together to continue their travels.
The original idea was drastically different: "My first idea was to do something that capitalised on the world over-run with Silurians and dinosaurs, with no plastics available; a kind of post-holocaust situation. I had this idea for an opening sequence inspired by Aliens, with a UNIT squad decimated by shrieking raptors, and a group of medics dragging a mortally wounded Brigadier to safety while an officer screams: "Somebody get me a doctor!" And then you hear the TARDIS materialising, and the theme music kicks in." 
For the purposes of this list, a "regeneration story" is one in which a regeneration is actually and initially depicted. For this reason The War Games is not included below, even though it is commonly thought of as a "regeneration story". It doesn't actually include a clear scene of regeneration, and the preponderance of stories in other media confirm that the Second Doctor did not regenerate at the end of it. Additionally, immediate post-regeneration stories, like the 2005 Children in Need Special — and ones like Castrovalva, where the regeneration sequence was replayed — are not included.
Regeneration is usually considered a biologic process exclusive to Time Lords and a few other species. However, some consider Regeneration and The Eclipse of the Korven to also be "regeneration stories", though neither describes anything close to a biological process. Korven is a particularly hard one to include in this list, because K9 is said to "regenerate" but is largely physically unchanged.