Ben and Susan are enjoying the peace and quiet of having the house all to themselves, but this is soon ruined by an Australian Backpacker called Craig, who turns up at the Harper's doorstep. Susan immediately invites him into the house, and he starts doing the jobs that Ben's always put off, much to Ben's annoyance, who just wants the house to himself and Susan. Things soon take a rather sinister twist for Ben when he realises that Craig may be his son, after a night of ‘fun' with his Mother. Janey soon takes a liking to the new guest and the pair of them go on a date, much to Ben's dismay, Susan then discovers the truth and it transpires that his brief fling happened when he and Susan were dating.