In London, the TED Idea Search brings together 10 voices from one of the world's most influential cultural capitals to compete for the opportunity to speak on the main stage at TED. From a civil engineer revealing the invisible infrastructure shaping our cities to a classical singer uncovering the erased history of women in music, the ideas on offer are both deeply personal and global in scope. When the lights come up, London doesn't hold back — and one speaker delivers a talk no one in that room will soon forget.