In the third episode of the 10th season we meet Petra Schubert for the first time. She is found by Semir and Tom along the highway. She has lost her memory and appears to be an important witness in a murder-case. Due to her memory-loss she can't the police anything, however the criminals want to muder her. Tom and Semir know to prevent this. Because she hasn't got anything (no home, no work) boss Engelhardt decides to offer her a job as her secretary. She replaces Andrea and gets in love with Tom. Both get a relationship but then Tom is murdered. Due to the memories she gets of Tom at the Cobra 11-office Petra can't work there any more and decides to quit her job at the start of the 11th season. The role of Petra is played by actress Martina Hill.