When family man Colin suddenly dies, his wife, Tess, and daughter, Cathy, get an even greater shock: Colin had been hiding a mistress, Marilyn, and another daughter, Cat, across town. Two weeks after the funeral, Cathy attempts to retrieve Colin’s ashes from his other family, while Tess decides it’s time to get back into the dating game.

Born five days apart, Cat and Cathy have different ideas about how to celebrate their upcoming birthdays: Cathy wants a quiet night with her fiancé, Marcus, while Cat thinks they should party together. Tess reconnects with a friend while Nordic walking.

After a breakdown at work, Cathy is put on compassionate leave and asked to attend grief counseling, but she hides what happened from her mother and fiancé. Cat wants to be Cathy’s maid of honor and offers to take care of the wedding dress.

Cathy boxes up her father’s things in preparation for selling the house, and Cat and Marilyn go overboard taking mementos. Later, Cathy teaches Cat how to ride a bike, while Marcus visits the dump.

Marilyn and Cat attend Cathy’s bachelorette party along with Cathy’s posh school friend and energetic aunt. Despite Cathy’s meticulously organized itinerary for the camping trip, things don’t go to plan.

Sisters Cat and Cathy reel from the news they have a secret brother, Callum—whom Cathy just snogged. Cat’s mom, Marilyn, is furious to learn she wasn’t Colin’s only mistress and sets about tracking down his other secret lover, Angela. Meanwhile, Cathy’s mom, Tess, decides to have some fun with her late husband’s legacy and embarks on an ill-advised luxury spending spree.