MPs will demand answers over the resignation of former child sexual abuse inquiry chair Dame Lowell Goddard from the Home Office's top civil servant.
Permanent secretary Mark Sedwill will be questioned at the Commons Home Affairs Committee on Tuesday.
Sedwill's appearance follows revelations that Dame Lowell resigned days after the Home Office was made aware of concerns about her "professionalism and competence".
Home Secretary Amber Rudd and her predecessor Theresa May have now been urged to reveal how much they knew.
Ms Rudd previously told the committee she believed the New Zealander, who denies allegations she used racist language, had quit because she was "homesick and lonely".
But on Friday night, the Home Office said it was made aware of worries about Dame Lowell's conduct on July 29, when Ms Rudd had taken over from Mrs May, who became Prime Minister on July 13.
Labour has called on Mrs May and Ms Rudd to provide assurances that there was no cover up.
Dame Lowell's replacement, Professor Alexis Jay, is expected to provide an update on the progress of an internal review of the inquiry's approach to its investigations on Monday.
Professor Jay is also due to appear before the Commons Home Affairs Committee on Tuesday.