He talks from his experience about what's real in politics and what's illusory - the borders between spin and substance, between reputation and reality.
For seven years, Geoff Mulgan worked at Number 10 as Tony Blair's strategic thinker and then head of policy.
He looks at political power, asking how much power the government really has in the face of change, and whether politicians have resorted, from lack of power and in order to be seen to be taking action, to gestures and spin.
He looks at perception and reality in politics - who, or what, brings decisive change? Does it come from the top, from the powerful, or from elsewhere? Drawing on his experience as a Downing Street advisor, he reflects on those who have simply looked busy, and those who really make the weather.