We come to the story that celebrated 40 years of the Fifth Doctor in 2022 with The Auton Infinity, a single six-part story forming the entirety of the second volume of Forty and the conclusion to the very short story arc where the Fifth Doctor is moved up and down his timeline to different points in his life. To give a quick rundown of this celebratory trilogy, the Fifth Doctor very early in his travels is suddenly moved into a future version of his own body where he experiences an adventure with Tegan and Nyssa while wondering what’s happened to Adric. This was Secrets of Telos and frankly a rather pointless sequel to The Tomb of the Cybermen. At the end the Doctor is once again moved along his timeline, this time backwards to when Adric was still alive where they experience a so-so adventure with the Ice Warriors. The end of the trilogy, The Auton Infinity, sees this storyline come to a head as the Doctor is once more moved along his timeline, this time towards the end of his travels as he's caught up in an adventure with Tegan and Turlough. They’ve arrived in Wales in the middle of a UNIT training exercise gone wrong as what was originally a fake alien invasion with soldiers in plastic alien masks has turned into a real attack as the Doctor, UNIT and the Brigadier once more face a threat from the Autons. But worse still is that the Autons have once again allied themselves with the Master in his grandest scheme yet.

As talented as Jon Culshaw is with his impersonations, it’s kind of ridiculous that they have him pulling triple duty by voicing three main characters; the Brigadier, Kamelion and the Master. Give it a few years and he’ll be playing every role I suppose!!!

The Auton Infinity marks the first proper full cast audio where the Doctor faces off with the Anthony Ainley incarnation of the Master. The reason why it took so long to get to this story goes all the way back to 2001 where Big Finish tried to get Ainley on board for their first Master story Dust Breeding but after failing to reach an agreement they went with Geoffrey Beevers to return as the Emaciated Master. Not only that but they even kill off the Ainley incarnation by revealing that his body was burned away by some form of energy, reverting the Master back to his emaciated figure. Unfortunately, they never managed to get Anthony Ainley on board before his death in 2004, since then his incarnation has had a very select few appearances in Big Finish (like literally I can count on one hand), but they’ve always tiptoed around having him properly involved in the story. Whether that be a narrated story that anyone can fill for, being an evil laugh in the background in Circular Time or using a human avatar in The End of the Line. The Auton Infinity finally brings the Ainley incarnation for a proper full cast clash with the Doctor, you can hardly celebrate 40 years of the Fifth Doctor without the Master. Especially this version who had numerous clashes with the Fifth Doctor throughout his era. Jon Culshaw’s impersonation of Anthony Ainley takes some getting used to, it’s one of those where you have to convince yourself of the character he’s playing when you first hear it. But he does nail Ainley’s cat-like demeanour, and honestly, I’ll take his performance if it means more stories from the Ainley incarnation going forward, this Master has been left out for far too long and it’ll be great to see what other clashes he can have with the Doctor. Which just leaves the Roger Delgado Master and I’m sure that story is coming soon.

Celebrating the Fifth Doctor’s 40th birthday you can definitely assume that this is packed with call-backs, references, tie-ins to other Fifth Doctor episodes and some familiar faces throughout his era making an appearance. In a lot of ways, The Auton Infinity is one big birthday party looking back on the Fifth Doctor’s life. But of course, it does have a lot of substance to it. The highlight of this story being the Autons themselves in what I can honestly say is my favourite story featuring the plastic terrors. The story dives into the origins of the Nestene Consciousness and sort of tips its hat to the lore in the novels where the Nestenes are one of the Great Old Ones (like the Great Intelligence, the Animus or Fenric), creatures who survived the collapse of the previous universe and became god-like beings in ours. There’s a lot of depth and development given to them compared to other stories.

As far as the overall story arc with the Doctor moved up and down his timeline, we get a satisfactory payoff as to who and why this has happened, and it culminates in a very beautiful ending where the Doctor opens up about what this incarnation really means to him. It’s one of my favourite Fifth Doctor scenes and Peter Davison really pours his heart out.

I wasn’t too sure going into this given how lacklustre the first box set was, but The Auton Infinity was a worthy celebration of the Fifth Doctor’s 40th birthday and if you’re a Fifth Doctor fan then this is worth listening to.