Since the announcement of Jorn Utzon's winning Sydney Opera House competition entry in early 1957 the project has excited controversy. Testing the very boundaries of technology, the gestation of this sublime building was long and fraught with problems, none more so than the departure of its architect in early 1966, never to return. With the building only a series of empty shells there was much for Utzon's successor, the 34-year old Sydney architect Peter Hall, to resolve. For both architects the Opera House would be a 'poisoned chalice' -- a compelling and unprecedented challenge, but one that presented almost insurmountable obstacles. But while Utzon's reputation has been restored, Hall's completion of the building has, ultimately, brought little recognition and enduring condemnation. It is the powerful myth of Utzon, the misunderstood architectural genius undone by the forces of conservatism, and of a building flawed by subsequent compromise, which has firmly taken root as the subtext in the popular imagination and in most narratives. The Poisoned Chalice examines in detail for the first time the extraordinary tangle of complex issues that confronted Hall and his team at the inception of the 'post-Utzon' phase, or Stage 3, of the project and the changes that were initiated to break the gridlock that stymied progress in early 1966. It draws on extensive, previously overlooked, primary sources -- including Hall's own papers -- and the recollections and archives of key participants to track the design evolution of the building's unresolved areas, focusing on the two main auditoria, the seating and the northern glass walls. It proposes that the changes introduced in the late 1960s were both justifiable and inevitable and that they have contributed substantially to the unprecedented success of the Opera House as an acclaimed performing arts centre. Ultimately, the book argues for a new narrative - a more inclusive, unbiased and balanced understanding of this magnificent building, unencumbered by the divisive undercurrents that have hitherto skewed most histories. AUTHOR: Dr Anne Watson's PhD thesis (Sydney University, 2014) was titled 'Peter Hall and the Sydney Opera House: the "lost" years 1966-1970'. She was formerly Curator of Architecture and Design, Powerhouse Museum, Sydney, and has published extensively, including most recently, '"That Immense and Complicated Thing": Peter Hall and the Challenge of a Career', in A Watson (ed), Building a Masterpiece: the Sydney Opera House (2nd ed, 2013); 'The Poisoned Chalice', Meanjin, Summer 2015; and Visionaries in Suburbia: Griffin Houses in the Sydney Landscape (ed, Walter Burley Griffin Society, 2015) colour and b/w images