In 12th century Palestine, the Doctor and his friends are drawn into the holy war between the forces of King Richard the Lionheart and the Saracen ruler Saladin.
The newly-regenerated Doctor arrives in Victorian London, and Clara Oswald struggles to embrace the man he has become. All the while, they reunite with the Paternoster Gang to investigate a series of combustions that have been occurring all around the city.
When disaster hits the Titanic, the Doctor uncovers a threat to the whole human race. Battling alongside aliens, saboteurs, robot Angels and a new friend called Astrid, can he stop the Christmas inferno?
An alien similar to Ra appears out of the Stargate, killing five soldiers and kidnapping another, a year after the original Stargate mission. A new team is assembled, including some old members, and they go in search of the missing soldier in order to find out how Ra could still be alive. Meanwhile, the alien Goa'uld kidnap Sha're and Skaara, implanting them with symbiotes and making them Goa'uld hosts.
The Doctor has retired to 1892 London. Despite the protests of his allies, he is determined to keep out of mankind's affairs. However, a governess named Clara has stumbled upon a plot which only the Doctor can unravel, involving the death of her predecessor in ice and the sinister Dr. Simeon, who controls monsters made of sentient snow. And there is another mystery afoot: Clara is the spitting image of Oswin Oswald, whom the Doctor saw die in the Dalek asylum...