She was a witness to the death of Heather Badcock (Babcock in the 1980 film), after-which she tried to blackmail the other guests whom she believed might have attempted murder on Marina Gregg. She is subsequently murdered with cyanide (HCN).
Ella had been the secretary of Jason Rudd ever since he made it big, and she would do anything for him. On the day of the fete, as she was directing the guests to meet Marina, she saw the murder of Heather. Realising that she had been murdered and that the glass had been intended for Marina, Ella decided to take matters into her own hands. She starts calling the guests from the party, hoping to blackmail the murderer. She used the telephone box in the village to make the call untraceable; however Ardwyck (or Marty) Fenn denounced her as the caller, because her sneeze from hay fever gives her away.
After another attack of hay fever, Ella used her atomizer, only to choke, collapse and die. Somebody had filled it with Prussic acid (aka cyanide), which was used as a weed-killer at the village manor where the Rudds and Ella are living during the production of the film.
Miss Marple, realising that Gladys Dixon had suggested that Heather had spilled her drink and maybe Ella had overheard this and called Marina to threaten her, which suggests Marina herself had placed the cyanide in her husband's secretary's inhaler. The reader or viewer is deceived by a "confusion of pronouns" when the event at the fete is recounted, specifically the pronoun "she." Which she?
- Ella was portrayed by Geraldine Chaplin in the 1980 Movie. In this adaptation Ella and Jason are having an affair, and she hopes Marina might eventually be out of the way. Ella is caught using the phone-box by Miss Marple and that she called Marina by accident.
- She was played by Elizabeth Garvie in the 1992 BBC Version. Here, she is also in love with Jason Rudd but he rejects her advances. She has asthma rather than the hay fever mentioned in the original, and she dies from poison inserted into her asthma inhaler. Dolly Bantry had noticed her cycling to the phone box just outside Gossington Hall and was puzzled about this and told Miss Marple. In this adaptation, Ella's last name is spelled Zeilinsky.
- She was played by Victoria Smurfit in the 2011 ITV Version. Her surname is changed from Zielinsky to Blunt. The reason for her murder was changed, mixing in elements from the 1980 film and the motive for Giuseppe's murder - Ella was attempting to blackmail the killer, but kept ringing the wrong people, because she knew someone at the reception had done it, until she learned something that led her to phoning Marina and pointing out what she had done. Her love of Jason remains, but there is no affair.