Threshold

A chief mechanic at a factory, haunted by apocalyptic nightmares, becomes a hero when Earth is invaded by a mysterious army bent on destruction.

Ba'al travels back in time and prevents the Stargate program from being started. SG-1 must somehow restore history.

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.

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.

A meeting in a London bus with jewel thief Lady Christina takes a turn for the worse for the Doctor when the bus takes a detour to a desert-like planet, where the deadly Swarm awaits.

A few years from now, Earth will have the first contact with an alien civilization. These aliens, known as Newcomers, slowly begin to be integrated into human society after years of quarantine.