The Forth Generation (audio story)

 was the third and final story in the audio anthology Old Friends, produced by Big Finish Productions. It was written by Roy Gill and featured Christopher Eccleston as the Ninth Doctor, Jon Culshaw as Brigadier Lethbridge-Stewart and Warren Brown as Sam Bishop.

Publisher's summary
The Forth Generation have emerged. The Doctor, the Brigadier, Sam and Fiona are at their mercy. Is there a way to defeat them? Has UNIT learned from the past? And can the enemy’s nature be changed for the future?

Plot
In March 1887, a foreman is recording the recent work on the Forth Bridge when Kreel and places him under Cyber-control, planning on using his foundry to create the Forth Generation.

In the early 2000s, the Forth Generation have awoken but are not complete without access to Cyber-Command. The Doctor realises that the Burryman was created to combat Kreel and uses burs to clog his respiratory system, but the Cybermen come to his defence and capture the Doctor and Fiona whilst the Brigadier and Sam go to collect an anti-Cyberman kit from a nearby UNIT facility. Under Cyber-control, Fiona calls Sam and learns about the kit before the Brigadier realises what is happening. She resists and, because of her strength, is taken into the bridge to be converted.

The Cybermen climb the bridge, accompanied by the Doctor, and hijack a train which Lawther and a UNIT courier carrying the Cyber kit are aboard. They take the case and the Doctor uses his sonic screwdriver to ensure that the Cyber-head inside will connect them to Cyber-Command only very slowly. The passengers are taken to be converted and a Cyberman designates himself as Cyber-Leader, deciding to partially convert Fiona into a Cyber-Planner to retain her knowledge without Kreel's permission due to his inferiority. Their attempted update causes the Cybermen to glitch, allowing the Doctor and several humans to flee, but Lawther is converted and the Cybermen learn from him of HMS Columba.

The Doctor regroups with the Brigadier and Sam on Inchcolm. The Brigadier stays behind whilst Commander Wardie takes the Columba to sea and the Doctor and Sam go to look at Fiona's research, hoping to find more weaknesses for Kreel and his Cybermen. They find that the Burryman always follows the same path and will have created a zone inside of which the Cybermen will feel as though they have transgressed. Some Cybermen emerge from the sea to convert the people of Edinburgh and others infiltrate the Columba and kill those aboard before demanding that the Brigadier give them the access codes. He contacts the Doctor via Sam's radio and is given a patch for an EMP generator.

The Doctor attempts to use the Memory Arch to restore Fiona, but she does not believe that she has the capacity to deal with her memories and takes him and Sam to the Cybermen. He makes her remember the path of the Burryman and activate it with the Cyber-network, creating a force field which expels the Cybermen from South Queensferry. She says that she is superior to the Cyber-Leader now and deletes him from the network before taking his place and ordering the Forth Generation to assemble underwater. The Doctor gives Fiona the Memory Arch and she decides to offer each of the Cybermen their identities, with Sam suggesting St Kilda as a new home.

Sam meets with Fiona, whose lifespan is now indefinite. He tells her that he is joining UNIT and gives her a kiss before leaving. The Brigadier expects the Doctor to disappear to the TARDIS, but he says a proper farewell and promises to think about the Brigadier's suggestion that he travel with somebody. The Brigadier says that he will be ready when they meet again, whenever that may be.

Cast

 * The Doctor - Christopher Eccleston
 * Brigadier Lethbridge-Stewart - Jon Culshaw
 * Sam Bishop - Warren Brown
 * Fiona McCall - Elinor Lawless
 * Cyber-Scout Kreel / Cybermen / Cyber-Head - Nicholas Briggs
 * Foreman / UNIT Courier / Sergeant Lowe - Alexander Cobb

Uncredited

 * Commander Jane Wardie - Amanda Drew
 * Cameron Lawther - Martin Quinn

Worldbuilding

 * Fiona is upgraded into a Cyber-Planner.
 * The Brigadier mentions neuristors.
 * Doris is heading to Edinburgh and then Glasgow.

Continuity

 * The Brigadier mentions the Cybermen's invasion of London and even walking up the steps of St. Paul's Cathedral. (TV: The Invasion)
 * The Ninth Doctor says not to believe all of the Cybermen's origins, especially the bit about Marinus or Planet 14, implying these origins to be untruthful. This is contrary to several accounts, which held these origins as true. According to one account, the Cybermen evolved from the Voord on Marinus, which was also called Planet 14. (COMIC: The World Shapers) According to an account by the Twelfth Doctor, Marinus and Planet 14 were two separate planets, and the Cybermen rose on both of them through parallel evolution. (TV: The Doctor Falls)
 * When threatened with conversion, the Brigadier responds, "Not today". The Brigadier would be posthumously converted into a Cyberman in 2014 only to break from his programming and save his daughter's life before encountering the Doctor one final time. (TV: Death in Heaven)