Ep 12. Army of Ghosts

In Doctor Who season 2 episode 13, titled "Army of Ghosts," the Doctor (David Tennant) and Rose (Billie Piper) arrive back on Earth to discover that every single person on the planet has experienced the appearance of a ghost at least once. These 'ghosts' seem to be harmless and are referred to as 'Mum' or 'Dad' by their loved ones.

However, the Doctor senses that something is not right and begins to investigate. His curiosity leads him to a company called the Torchwood Institute, a top-secret organization that has established itself as the world's leading authority on the paranormal.

As the Doctor and Rose delve deeper into the mystery of the ghosts, they uncover a terrifying truth - the ghosts are actually Cybermen, a race of highly advanced cyborgs who are seeking to take over the planet. In order to do so, they have devised a clever plan to infiltrate human society under the guise of ghosts and slowly take over.

The Doctor and Rose are horrified at the Cybermen's plan and immediately set out to stop them. Along the way, they encounter a group of rebels who are also trying to fight against the Cybermen's invasion.

As the Doctor and the rebels work to stop the Cybermen, the Torchwood Institute reveals that they have been keeping their own secrets and have actually been working with the Cybermen all along. The Doctor and Rose are shocked and devastated by this revelation, particularly when one of their own companions is revealed to be working with Torchwood.

With betrayal and danger at every turn, the Doctor and Rose must race against time to stop the Cybermen and save the planet from the Army of Ghosts.

This action-packed episode features thrilling battles, emotional moments, and shocking plot twists that will keep viewers on the edge of their seats. With standout performances from Tennant, Piper, and guest star Noel Clarke as Mickey Smith, Army of Ghosts is a must-see episode for Doctor Who fans.