Distractions

The Seventh Doctor is brooding when Ace asks him about his "old study", which they head for. He wonders why he hasn't been able to take his TARDIS away from Earth recently, and why they've encountered creatures that should never have been there. When they arrive at the "study", it's actually the secondary control room, and he remembers when he previously used it. After all this time, a part of the Mandragora Helix is still aboard the TARDIS, and the Doctor fears it is now powerful enough to direct the path of the TARDIS as well as draw other forces to Earth. As, he and Ace leave the control room, helix energy crackles into life.