Dr. Summerbee gets a visit from her old friend actress Heather Conway over Christmas. Her stay is not a courtesy call though. She is hiding from somebody and that somebody is close on her heels. Emma Turner is blind and very dependent on her guide dog Peggy. But one day Peggy has disappeared. The dog is Emma's only company over the holidays, but despite a thorough police search there is no trace of Peggy. Fortunately an article in the local news paper turns up a lead. Joyce Jowett has become the new chairman of the local finance committee. She is very interested in the old folks' Christmas party and Vernon Scripps promise her to supply a Christmas tree with lights and everything. Getting a tree is fairly easy, but David has a small mishap with the coloured lights.