>> as the country watched, white house counsel john dean turn on his president. >> i began by telling the president that there was a cancer growing on the presidency. >> dean testified the watergate burglars were blackmailing white house aides. >> the white house was now directly subject to blackmail and i didn't know how to handle it. >> i told him i could only make an senate it might be as high as a million or more. he told me, that was no problem. >> it was john dean's word against the president of the united states. >> nothing less than richard nixon's presidency may ride on whether the world believes john dean or not. >> most republicans continued to stand by their president. but then, from a little known white house aide, a dramatic twist. >> my name is alexander butterfield. >> mr. butterfield, are you aware of the installation of any