After retiring from teaching literature in Dublin, Harry finds herself unable to cope with a life of leisure. Instead, she begins working as an amateur detective, much to the chagrin of her strict policeman son, Charlie.
Harry and Fergus' fame attracts a woman who seeks their help to find out the truth about her husband's mysterious death. Despite Harry's hesitation, her curiosity pushes her to delve into the case.
Harry recruits her granddaughter, Lola, to go undercover inside a girls' school, where they try to catch a bank robber who has committed murder so that he can fake his death and disappear.
A serial killer takes inspiration from Dostoyevsky's novel Crime and Punishment, and he challenges Harry to catch him before he commits a new crime.
At an elegant dinner party at a former colleague of Harry's, things turn disastrous when all the guests start to vomit, before it is discovered that the source of the sickness is a corpse hidden in the house's well.
A violent storm traps Harry, Fergus and Lola inside a pub. While they think the worst that could happen is waiting, they discover a kidnap victim in a nearby car.
During a family video call, a wealthy woman is strangled to death. Her daughter enlists the help of the Wild/Reid Detective Agency to solve the mystery and uncover the killer.
A recovering addict, Zoe McCann, is kidnapped and wakes up in a forest wearing an old dress. She finds herself in a race with her mind and her resilience to stay alive.