Former Cabinet ministers Lord Mandelson and Tessa Jowell will kick off a potentially dramatic week at the Leveson inquiry.
The peer witnessed Rupert Murdoch's links with the governments of Tony Blair and Gordon Brown at close quarters, while Jowell settled a phone hacking case against the media mogul's News International for £200,000 last year.
Over the coming days the media standards probe is due to hear from other senior politicians including ex-home secretaries Alan Johnson and John Reid, and Labour MP Tom Watson.
Top journalists Andrew Marr and Jeremy Paxman are also set to appear.
But the most high-profile session is likely to be Thursday, when Adam Smith, former special adviser to Culture Secretary Jeremy Hunt is listed.
Smith quit last month after admitting he had inappropriate discussions over the BSkyB bid with News Corp lobbyist Fred Michel - who is also giving evidence.
Their comments to the inquiry could prove vital in deciding the fate of Hunt, whose career is still hanging in the balance.