What is the exposition of "Appointment With Death"?

In the exposition, we learn that a group has taken a cruise to the Holy Land. While there, Mrs. Boynton is found dead, and although it is made to look like an accidental death.... Poirot has other ideas. We also learn that Mrs. Boynton has blackmailed a lawyer to "fix" her late husband's will, that she was involved in an affair, and that her husband's children are looking into the change in their father's will.