Every family has its secrets but Agnes Brown is concerned that her family are keeping too many. Cathy her daughter doesn?t want her to meet her new boyfriend. Her son Mark won't reveal why he?s been thrown out by his feisty wife Betty. And her younger son Dermot has lied to his fiancée?s well-to-do parents about his job.
Betty and Mrs Brown meet to discuss Mark's problem, and surprise, surprise they come to blows. Unfortunately the row happens right in front of Dermot's posh future mother-in-law, who has come round to discuss wedding arrangements. Horrified by what she witnesses, Mrs Nicholson decides that the Brown family are so rough she won?t have them at the wedding.
Mrs Brown sees another man by Betty?s side and comes to the conclusion that Betty is having an affair and that?s the reason that Betty and Mark have fallen out. When she finally confronts Betty, Agnes is baffled to discover that Mark is the one who has something to hide? and it?s a guilty secret for which Agnes has only herself to blame.