Agnes Brown has family troubles to contend with: her son Dermot has fallen out with Maria Nicholson, his long-term girlfriend, and Grandad is feeling poorly.
After a sleepless night, Mrs Brown decides to try to sort out Dermot and Maria's problem by giving Maria the benefit of her advice. But her heart-to-heart with Maria only succeeds in making the dispute worse. So Mrs. Brown's daughter Cathy intervenes. She's a psychology student, and offers Dermot and Maria a counselling session. A dismayed Mrs. Brown can't help interfering, and the session quickly descends into a blazing row between her and Cathy... with an effect on Dermot and Maria that not even Agnes Brown could have predicted.
Meanwhile, Grandad ends up in hospital when Dr. Flynn's attempt to read his temperature goes dramatically wrong. And Cathy reveals the electrifying secret of how she keeps dodgy men at bay.