A clear straight road; a dry morning; a good car. Why should a businessman crash into a bridge support at 80 mph? Why are there no skid marks? When the post-mortem reveals him to have died as a result of the impact, and not from physical causes, and the car is found to be mechanically sound – what other reason could there be for the accident? Or was it an accident? Guest stars Petra Markham and Simon Oates.