Demented tells the hilarious story of a doomed bank heist involving a divorced man going through the man-opause, his dementia-suffering father, his vengeful wheelchair-bound neighbour and an avaricious young woman. Andrew is divorced and living in a pensioner's bungalow taking care of his father who has dementia. Keith, his next door neighbour is in a wheelchair after a road accident which wasn't his fault. Keith's girlfriend Felicity is listed as his care person but is more likely to borrow his car, money and anything else she wants. Felicity works at the bank, where the manager is the driver who put Keith in a wheelchair. At first Andrew doesn't want to know until Felicity tells him a cure for dementia might be available but only at a substantial cost and his father shows his determination not to give his final years over to the disease without a fight. What could possibly go wrong?