Michael Wolff's book, Fire and Fury paints an unflattering picture of US President Donald Trump, questioning his mental health, and his ability to grasp basic policy. But the former TV star says it’s completely false, and calls the author a fraud. A large part of the book is based on conversations Michael Wolff had with Steve Bannon, Trump's former chief strategist, and a man at the heart of the Trump White House up until he was fired. So how much damage could this latest scandal cause the US president? Could it actually bring down him?