Thirteen at Dinner (1985)

Hercule Poirot appears on a TV talk show with actor Bryan Martin who is making an action/detective movie with Jane Wilkinson. He also meets impressionist Carlotta Adams. They all go to a party and Jane asks him and Captain Hastings to go and meet her husband, Lord Edgware in regards to a divorce. They do so, to discover that the Lord had already granted her a divorce. Jane is delighted but drops hints that she could have killed the Lord if he didn't grant her the divorce. The next day Lord Edgware is found dead and all the staff at the Lord's house swear that Jane was the one who did it but witnesses at another Lord's party swear that Jane was with them. Carlotta then dies and Poirot must investigate as Inspector Japp is determined to put Jane away...