This is a story that Angus Grigg has wanted to tell for five years.It's got all the elements – money, insiders and power – but until recently, the rise of the consulting giants and how they've infiltrated government was confined to the business pages.Then the PwC tax scandal happened.This week on Four Corners, we investigate PwC's equally large and consequential rivals, and their huge influence in Canberra.Top of our list is KPMG, which has billed the Department of Defence a staggering $1.3 billion over the past five years.Whistleblowers tell us how it repeatedly over-charged the department – and you the taxpayer – for work never completed, and even invoiced for a consultant who wasn't on a project.And we don't stop there.