Pupils at a prestigious UK private girls' school opened their English Literature exam papers only to discover they has been taught the wrong book.
The teenagers at £37,000-a-year ($72,000) Malvern St James found there were no questions on Spies, the Michael Frayn novel they had spent two years studying for the International GCSE.
Now some parents at the boarding school in Worcestershire claim their children have suffered stress as a result of the mistake.
The headmistress has apologised and said the issue is being investigated. She has appealed to the Cambridge International for "special consideration" to be made when the papers are marked.
The IGCSE is an alternative international qualification to GCSEs and is preferred by many independent schools.
Spies was wrongly included in a list of books on the syllabus that includes Hard Times by Charles Dickens and Mansfield Park by Jane Austen. One parent told The Independent her daughter had been left 'stressed out' by the incident, adding it could "scar students for life".
"It has been a complete utter waste of time for two years," the mother said. "They have let her down completely.
"I want compensation and I want heads to roll. For that amount of money they should not be making mistakes. You have to be responsible of what your teachers are doing. For two years they have been studying the wrong book. It is a joke."
In a statement, headmistress Olivera Raraty said: "There was an issue with one section of an IGCSE English Literature paper sat by one group of students in Year 11 on May 15. One of the texts taught to this group was incorrect.
"The problem was identified immediately, and we are now working with the exam board in question so that no girl should be disadvantaged.
"Fortunately, all exam boards have procedures in place to deal with this type of incident and we meet the criteria for 'special consideration'. Meanwhile a full internal investigation is underway. We apologise wholeheartedly."
Cambridge International sets out strict rules for applying "special consideration", a post-exam adjustment to a candidate's mark usually given to pupils who face difficult personal circumstances including illness or bereavement.
However, perhaps fortunately for the girls of Malvern St James, a new addition to its handbook foresees their problem.
It says: "Where candidates have been prepared for an incorrect work, we may, at our discretion, consider applications for special consideration".
It warns that even where marks are changed, only "minor adjustments" will be made so as not to "jeopardise the assessment standard". The board said yesterday: "We were contacted by the school as they discovered they had taught the wrong English Literature text.
"We recognise that this is distressing for the students involved. We have asked the school to follow our procedures for rare situations like this by submitting a request for special consideration on behalf of the students affected."