Rupert Murdoch and his son James are due to appear before MPs to face their intensely-awaited grilling on the News of the World phone-hacking scandal.
The two men will face the Commons Culture, Media and Sport Committee to answer questions over their involvement in the affair which has engulfed their media empire and rocked police and politicians to the core .
In what promises to be a dramatic day at Westminster, the two most high-profile casualties of the scandal so far - former Metropolitan Police Commissioner Sir Paul Stephenson and ex-assistant commissioner John Yates - will also be giving evidence to another committee in the same building.
Mr Murdoch and his son agreed to appear only after the committee issued summonses ordering them to attend - with the threat of fines or even imprisonment if they failed to turn up.
In a defiant interview last week with the Wall Street Journal, owned by his News Corp group, Rupert Murdoch said he intended to use the hearing to expose some of the "total lies" issued about his organisation.
Since then, however, he has struck a notably more conciliatory tone - taking out full-page advertisements in rival newspapers to apologise for what had happened.
They are due to appear before the committee at 2.30pm in the Wilson Room in Portcullis House, opposite the House of Commons. They will be followed by Rebekah Brooks, former chief executive of News International - News Corp's UK newspaper publishing arm. She will now appear separately - about an hour later - having finally resigned on Friday.
She is a key figure having been editor of the News of the World when murdered schoolgirl Milly Dowler's phone was hacked in 2002 and having previously told the committee that News International paid police officers. However her arrest on Sunday by detectives investigating the phone-hacking allegations may complicate the questioning.
Before that, along the corridor in the Grimond Room, Sir Paul and Mr Yates along with Scotland Yard's director of public affairs Dick Fedorcio, will give evidence to the Commons Home Affairs Committee.
Mr Yates has been under fire over his decision in 2009 not to reopen the original 2006 police investigation into phone hacking.