. . "The tenth anniversary episode of Doctor Who was marked with this, the first \"Multi-Doctor\" episode, a concept which would be used several more times over the coming years. The Doctor is investigating the appearance of a mysterious blob-like creature which, it transpires, is hunting him down. Reluctantly, he calls on the Time Lords for help. Unfortunately, they're a bit preoccupied with the black hole draining all their energy, so they send his past selves to help. The First Doctor is caught in a time eddy and can only advise via the TARDIS viewscreen, but he deduces that the blob creature is a \"time bridge\". The Third Doctor and Jo allow it to capture them and they are transported to a world of antimatter beyond the troublesome black hole. Meanwhile, back on Earth, the Second Doctor, the Brigadier and Sergeant Benton take refuge in the TARDIS. The First Doctor tells him to switch off the forcefield and the TARDIS (and with it the UNIT HQ) are all transported to the antimatter world. It turns out that the problem is Omega, a renegade Time Lord. Omega was a stellar engineer, and his experiments enabled the Time Lords to develop time travel. But one of his experiments went wrong and trapped him in the antimatter universe. Now he wants to return, but needs a matter counterpart to take his place, and he wants the Doctor. Driven mad by his isolation and corroded so that only his will survives, he threatens to destroy the universe, but he is tricked into picking up the Second Doctor's recorder - the only thing not converted to antimatter when they travelled through the black hole - and is destroyed. As a reward for saving the universe, The Doctor's exile is lifted and he is able to use his TARDIS normally once more."@en . . . . . . "Doctor Who/Recap/S10 E1 The Three Doctors"@en . . . . . "The tenth anniversary episode of Doctor Who was marked with this, the first \"Multi-Doctor\" episode, a concept which would be used several more times over the coming years. The Doctor is investigating the appearance of a mysterious blob-like creature which, it transpires, is hunting him down. Reluctantly, he calls on the Time Lords for help. Unfortunately, they're a bit preoccupied with the black hole draining all their energy, so they send his past selves to help. The First Doctor is caught in a time eddy and can only advise via the TARDIS viewscreen, but he deduces that the blob creature is a \"time bridge\". The Third Doctor and Jo allow it to capture them and they are transported to a world of antimatter beyond the troublesome black hole."@en . .