The BBC have officially released titles and episode details for the first four episodes of Season 7b, which premiers March 30, along with new desktops in "movie poster" style, following the trend from last year's episodes.

Follow the title links to download the desktops.

The Bells of Saint John
The Doctor’s search for Clara Oswald brings him to modern day London, where wifi is everywhere. Humanity lives in a wifi soup. But something dangerous is lurking in the signals, picking off minds and imprisoning them. As Clara becomes the target of this insidious menace, the Doctor races to save her and the world from an ancient enemy.

The Rings of Akhaten
Clara wants to see something awesome, so the Doctor whisks her off to the inhabited rings of the planet Akhaten, where the Festival of Offerings is in full swing. Clara meets the young Queen of Years as the pilgrims and natives ready for the ceremony. But something is stirring in the pyramid, and a sacrifice will be demanded.

Cold War
The Doctor and Clara land on a damaged Russian Submarine in 1983 as it spirals out of control into the ocean depths. An alien creature is loose on board, having escaped from a block of Arctic ice. With tempers flaring and a cargo of nuclear weapons on board, it’s not just the crew but the whole of humanity at stake!

Hide
Clara and the Doctor arrive at Caliburn House, a haunted mansion sat alone on a desolate moor. Within its walls, a ghost hunting Professor and a gifted psychic are searching for the Witch of the Well. Her apparition appears throughout the history of the building, but is she really a ghost? And what is chasing her?