Death on the Nile is one of those favorites. I remember the first time I read it, as a 15-year-old on my way back from vacation in Rio de Jenario. 25 years and at least a dozen revisits later, I still flash back to my mother retrieving me from the airport snack bar where I was pouring over the plan of the S.S. Karnak so intently I hadn't heard our flight announced.
The plot of Death on the Nile follows the locked room template. Someone murders Lynnette Doyle while she's on a honeymoon cruise in Egypt. No one other than her fellow passengers could have committed the crime, most of them have both alibis and motives, and it is up to Hercule Poirot to deduce the identity of the murderer. Of course, I know who murdered Lynnette Doyle, and why, and how. That allows me to enjoy the setting and the characters, especially the Allertons (does Mrs. Allerton really not know what her son is up to?), Simon Doyle (is he really the sweet, stolid, doting husband he appears to be?) and Cornelia Robeson (is she dim, or has she been typecast by her family?). Rereading Death on the Nile, or any Christie novel, is untaxing pleasure reading in its most basic form.