It's coming up to Christmas, and Mike's mum is staying. Betty wants to be helpful, but it isn't long before she is driving Mike and Alison round the bend. Betty has overstayed her welcome, but Alison and Mike don't quite have the heart to tell her. Just as she decides to leave of her own volition, Betty suspects something is terribly wrong at Button House. She adopts extreme measures to make the house safe and in doing so endangers the resident Ghosts – will they come out of this unscathed?

Mike and Alison receive a life-changing offer beyond their wildest dreams. Still reeling from the news and anxious to discuss it, they are interrupted by a heartbroken Obi, who has been suddenly dumped by a strangely callous Brenda. Alison and Mike agree to reconvene with lists of pros and cons. At first, Obi's romantic woes find a sympathetic ear in eternally lovelorn Thomas, but even he tires of Obi's self-pity. Meanwhile, Alison must fend off the ghosts, desperate to sway her decision.

Robin has an epiphany that has a far-reaching impact on the rest of the ghosts, who each struggle to believe his prediction. Alison suggests a spontaneous night out with Mike, just like the old days! They try to get the old gang together but with such short notice, only Obi and his new girlfriend Brenda are free. Despite Alison's efforts to plan the best night ever, the evening doesn't quite meet her expectations, and the couple are left pondering how much their lives are changing.

The ghosts are officially bored, and Pat comes up with new entertainment for the gang. Mike and Alison host their international buyer at Button House in order to confirm the land sale, but Mike's antics threaten the whole deal – can he pull it back in time? Humphrey is offered a fresh perspective on his strained marriage and finally learns some French, with a little help from a most unexpected source.

Alison and Mike are forced to cosy up to Barclay if their plan to sell some land to the golf consortium is going to work. Elsewhere, Alison is involved in a silent negotiation of her own – she has designs on Lady Button's bedroom but can't quite muster the courage to ask her outright if she would consider relocating. The ghosts become fixated on solving the mystery of Kitty's death.

In a bid to make some much-needed money, Alison and Mike look into selling some land. The plan proves far from straightforward however, with Lady Button up in arms at the mere thought of losing some of her beloved estate. Thomas enters a competition that he hopes will finally see him become a published poet, but hearing Lady Button speak so passionately about Button House gives him an idea or two... Pat and Julian are locked in a dispute, and it is Robin who offers a surprising pearl of wisdom.

Mike approaches Alison to discuss their finances following the loss of their B&B business. However, Alison is more preoccupied with plotting revenge on the Ghosts for April Fool's Day and recruits a playful Humphrey to execute her plans.

But who will prove the hardest to fool? Meanwhile, Mike is shocked to find someone from their insurance company on his doorstep – an unannounced visit to check the details of the gatehouse fire. Can Mike convince her that lightning really can strike thrice?