“Mademoiselle, I beseech you, do not do what you are doing.” “Leave dear Linnet alone, you mean!” “It is deeper than that. Do not open your heart to evil.” Her lips fell apart; a look of bewilderment came into her eyes. Poirot went on gravely: “Because—if you do—evil will come…Yes, very surely evil will come…It will enter in and make its home within you, and after a little while it will no longer be possible to drive it out.” Jacqueline stared at him. Her glance seemed to waver, to flicker uncertainly. She said: “I—don’t know—” Then she cried out definitely, “You can’t stop me.” “No,” said Hercule Poirot. “I cannot stop you.” His voice was sad.”
―
Agatha Christie,
Death on the Nile