The puppet of Empress Sisi was one of the wooden puppets created using Gramm's Cyber-Technology. She was modelled on Empress Sisi, could speak and, unlike most other puppets, had a relatively large vocabulary and natural intonations.
Doing Johan Drossel's bidding, she managed to persuade Alfred Stahlbaum that the Empress herself had paid a visit to Marionettenburg. In this role, she asked Stahlbaum to work together with Drossel. At first, she even fooled Countess Mitzi Wittenmeier, kept prisoner by Drossel. Thinking this to be her friend, the Empress, Mitzi beckoned her to run away from this dangerous man. The Eighth Doctor, however, saw through her act and demonstrated that she is made of wood by snapping her head off.