In the paper the author pays attention to how A. Christie in particular texts rewrites the fixed codes of the detective genre by their variations. For instance in the 'Murder on the Orient Express', she symmetrically turns the code of the detective story: a criminal used to be found as one of the persons from the closed circle of suspicious people - in case of the Orient Express - each of those who took part in the case are the criminals except the one who was considered to be a suspicious. In the story 'The Murder of Roger Ackroyd' the murderer is a narrator, who concealed his crime (that course was not new: before Christie it had been used by Cechov, M. Leblanc a S. Elvestad). In 'The A.B.C. Murders', Christie first simulated the method typical for the criminal genre, than the text finally resulted in the detective story according to all literary rules. She also introduced 'topoi' of camouflaging murders later used many times in the detective stories. We can follow up further plots in the texts transforming the mentioned proto-text of A. Christie (M. P. Schaffer, J. Symons, A. Kristof, F. Vargas).