sentences:  Originally, writer Douglas Adams presented a wholly different idea for the season's six-part finale, involving the Doctor's retirement from adventuring.Facing resistance from producer Graham Williams, Adams chose to avoid work on a replacement, under the expectation that time pressures would eventually force the producer's hand and allow his idea to be used.Ultimately, however, Williams forced Adams to conceive a new story as a last-minute replacement, which became "Shada".