The film introduces the methods of deep seismic profiling by way of portraying seismic experiments that were carried out in 1985/86 to explore the structure of the Earth's crust in one of the target areas of West Germany's Continental Deep Drilling Program (KTB). The first part focusses on the basic concepts of reflection seismic analysis and on data acquisition by the Vibroseismic method. Essential steps of data processing are briefly illustrated. The second part traces complex refraction seismic experiments from the preparation of the shot-holes through the simultaneous movement of three different receiver spreads. Last, the resulting compressional-wave velocity model is combined with the seismic reflection pattern to aid a conceptual geological interpretation of the continental crust in a suspected suture zone to be tested by an ultra-deep drill hole.