It's a Living S02E02 - All My Son

A woman who had a brief one-night encounter with Sonny at a New Year's Eve party in 1972 shows up at Above The Top in order to tell Sonny that he could be the father of this woman's child, which later turns out to be a rouse by the woman in question so she can get some money from him due to her not being able to find an adequate job for herself and her son Arthur.  Meanwhile, Dot brings a brown mouse to work which later escapes from the shoebox that it was in, causing panic amongst the waitresses.  Later on, Nancy accidentally kills the rodent in question while she questions Dot about it.