The Bells of St. John
We’ve seen two versions of Clara Oswald, but this introduces the modern day Clara who will accompany The Doctor. The story deals with a new nemesis, the Spoonheads, who will battle the Doctor as he discovers something sinister is lurking in the Wi-Fi in contemporary London.
The Rings of Akhaten
Perhaps the most mysterious episode of the season at this point, the story is set around an alien planet.
The Cold War
The Ice Warriors, the most significant alien race from the classic series that had yet to make an appearance in the modern-era, finally return to the Who-universe. Mark Gatiss penned this underwater siege episode, set around a Russian submarine and an ice base, with the Ice Warriors said to be shown without their battle armor at one point. Unlike the Silurians which got a complete redesign, the new Ice Warrior look is said to be remarkably faithful to the classic series. David Warner guest stars as the Ice Lord.
The Hider in the House (aka. Phantoms of the Hex)
A classic Victorian Gothic ghost story guest starring Dougray Scott as a professor also trying to find the truth behind the supernatural shenanigans.
Journey to the Centre of the TARDIS
A story that takes place within the TARDIS itself as characters have to run around within the multi-dimensional environment as they race towards its very heart – the Eye of Harmony (last seen in the 1996 telemovie) – to stop some sort of cataclysm from happening.
The Crimson Horror
Dame Diana Rigg and her daughter Rachael Stirling guest star in this “very camp” Victorian-era period episode in which Rigg’s character has opened a factory in her hometown – a factory that produces no visible smoke or pollution, and those who step into it don’t step out. Clara gets taken for ‘processing’ at one point. The top hatted, no-faced creatures with teeth glimpsed in the ‘Coming Soon’ trailer seem to be from this episode.
The Last Cyberman
The Neil Gaiman-penned episode is apparently set on what’s described as a fantastical theme park world. The Cybermen return with a slight redesign, but it’s unsure right now if this is the return of the original Mondasian Cybermen. Gaiman’s brief was to make the Cybermen scary again – something not really seen since the colder, deadlier incarnations of the second Doctor era.
The season finale. Alex Kingston’s River Song makes her only appearance this season. Many of the characters from the Christmas special re-appear here including Richard E. Grant’s Dr. Simeon, the Sontaran Strax, the Silurian Madame Vastra and her wife Jenny.
Then there’s the 50th Anniversary special episode to air in November, not to be confused with the already in production and separate telemovie “An Adventure in Space and Time” about the creation of the show. Filming on the 50th special begins in April, and it seems a certainty that at least one (if not several) of the earlier incarnations of The Doctor will be returning. The same goes for some of the previous companions. There’s also talk of it being a feature-length episode.
Source: Dark Horizons