Perry Mason: The Case of the Glass Coffin.

David Katz is a world famous magician and he comes to Denver with his group to perform for a charity gala for disabled children. Also there is Perry and Della as all three are supporters of the charity. Kate Ford, an assistant with an arrogant attitude, tells David that she is, from now on, going to do an illusion in which an assistant is raised in a glass coffin only to disappear when the coffin is opened up in the air (while the assistant climbs out before the coffin is raised.) After a one night stand with David, Kate is pregnant and she blackmails David with this. David and his wife Judy can't have children so that comes as a double blow to them. However Kate, with her attitude, creates much hatred at her from the rest of the group. At the gala, the glass coffin is raised but when it opens Kate's dead body falls to the ground - strangled.