Agnes becomes concerned when Dermot announces he wants to ask his childhood friend Buster, a known criminal, to be his best man. Mrs Brown is distracted when her neighbour Winnie's husband is rushed to hospital, leaving her son trying to raise money for his wedding by becoming embroiled in a money-making scam with his friend.

Newlyweds Dermot and Maria argue over whether they should buy their own home. Meanwhile, Mrs Brown tries to make Grandad happy by secretly staging a funeral for him, but the plans go awry when she mistakes two Mormons - who have been stealing Father Quinn's parishioners - for the men who are supposed to be delivering the coffin.

Agnes Brown’s son, Dermot, and his new wife, Maria, have a baby on the way, and they are desperate for a place of their own, as the smash-hit comedy written by and starring Brendan O’Carroll continues. The newlyweds just can’t afford to move out, but Mrs Brown has a plan to help her son. Loving mother that she is, Agnes has promised the couple the money from Grandad’s life insurance policy payout for a deposit for their own home. There’s just one minor hitch – Grandad is not dead. Caught between a suspicious insurance company and her God-fearing son, Trevor, Agnes has to resort to desperate measures to keep Grandad out of sight and her dream alive.

Agnes is upset that her son Trevor has been called back to the missions in Africa, but is determined to give him a massive send-off to remind him what a loving family he has back home in Ireland. Meanwhile, daughter Cathy's family counseling session descends into chaos, and Buster and Dermot run into trouble with a circus lion. The only person having a good day is neighbour Winnie: thanks to his new medication, her husband Jackos's libido is back. But while Winnie delights in reminiscing about her former bedroom antics, Agnes makes a shocking discovery.

A secretive phone call from a solicitor to Mrs Brown leaves her children suspecting one of them may be adopted, while Father Quinn returns from rehab and asks Agnes to help out at his annual garden party - although as she proceeds to drive him crazy with a smartphone, his recovery may be short-lived. Meanwhile, Cathy receives a blast from the past, Rory and Dino have a bust-up, and Mark and Betty deliver bad news - they are leaving for Australia right away.

The Browns are excited as preparations for Rory and Dino's big day are in full swing - although Agnes's mood is dampened when she meets flamboyant celebrity wedding planner La La Doggy. The foul-mouthed matriarch also clashes with Father Damien when he raises some religious concerns about the ceremony - and to top it all off, she gets more than she bargained for when she invites Cathy's boyfriend's parents over for the evening.

Agnes is well-pleased with her state of the art remote-controlled Christmas tree - though less so with Buster's exploding crackers. She reluctantly agrees to help Mark and Betty by finding out what their son Bono wants from Santa before hosting the family's pre-Christmas party, which makes her very cross when nobody - especially Hillary - will play by the rules in her party games, as usual. Grandad's charades contribution turns out to be a mild heart attack but, after the guests have gone, he still has fun at Agnes's expense with the Christmas tree. Agnes resorts to desperate measures to discover what Bono wants from Santa - whose visit is not what she expected. However the whole family comes together for their Christmas Day musical finale.

Agnes prepares for her New Year's Eve party although half the guests have reasons for not coming to it. She is also perturbed that Mark and Betty want to send Bono to the very rough local school and is somewhat harassed when stern Father McBride persuades her to look after a parrot that belonged to Maria's recently deceased auntie. After having a mishap with some aerosol glue which she mistook for deodorant and accidentally bringing on Dino's food allergy Agnes learns that the parrot was living in a house of ill repute not unknown to Father McBride, a fact which comes...