Robin simply shook her head in amazement, still holding on to the rail for dear life.<em>Right, simple,</em>she thought,<em>Just fly toward the impending destruction of a giant, impossible tree... and use the back entrance to get even closer to a fleet of destructive, war-crazy mutants who have a huge vendetta against you. Of course. Why didn't I think of that?</em><br/><br/>Somehow, she kept her thoughts to herself, not wanting to distract the Doctor. Wincing as he opened the door and the blinding flash of light filled the TARDIS, she nevertheless joined him just outside. The root was an astounding size, and the cave gaped open like the mouth of some prehistoric monster. When she stood next to him, she slid her hand into his, linking their fingers together.<br/><br/>"Okay," she said quietly, stunned by the immensity of the tree. "I'm ready." And in the back of her mind, the beeping started again, rhythmic and regular and incessant.