Earlier this year, inspectors criticised Glan Ely high school in Cardiff for failing to provide satisfactory education for the 780 pupils aged 11-18 drawn mainly from the sprawling Ely estate.
Underachievement in many subjects was identified, with teaching standards in a third of classes deemed unsatisfactory, and only barely satisfactory in many others.
Peter Leech takes over as head from David Emerson-Thomas next month, and four more governors are being appointed by South Glamorgan education authority, which drew up the Pounds 500,000 rescue package jointly with the governing body.
The timetable is being revamped as part of efforts to lift Glan Ely from bottom place in the league table of Welsh secondary schools. only 5 per cent of the school's 15-year-olds achieved GCSE grades A to C this year, against a Welsh average of 41 per cent.
Efforts are being made to widen the range of after-hours activities - particularly important in an area battling against high levels of truancy and social stress.
The inspectors say they uncovered "an imbalance" in the school's budget between staff costs and cash directed to learning resources.
Parents will be supplied with regular progress reports. Teachers - the school has 49.7 full-time equivalents - will be given training to upgrade practices and to increase knowledge, particularly in technology, science and history.
A tight rein will be maintained, with inspections every term to monitor progress, and Mr Hague says: "I shall not hesitate to set up an education association to run the school if progress is not satisfactory."
The school is the first of the 227 secondaries in Wales to be described as failing. Only three of the principality's 1,698 primary schools have so far been identified as failing.