Murder at the Gallop

When a wealthy old man appears to have been "frightened to death" by a cat, Miss Jane Marple suspects one of his four relatives, all heirs to his estate, of his murder.
Miss Marple and Mr. Stringer are witnesses to the death by heart attack of elderly, rich Mr. Enderby. Yet they have their doubts about what happened. The police don't believe them, thus leading Miss Marple to yet again investigate by herself.