When Grandma Simms comes from the farm to visit her daughter, she finds a situation which is not to her liking. It seems that her daughter, Mrs. Abbott, has become a social climber since the death of her husband. Because of this, the three Abbott children and Sadie, the maid, are having a miserable time.
The very day Grandma arrives, Mrs. Abbott is bringing three upper-crust guests home for the weekend. One of them is rich and snobbish Arthur Carlson, who, Mrs. Abbott insists her daughter must marry although she loves Brandon, a veterinarian assistant. Another of her guests is Miss Quelch, an unlikable spinster, who runs an exclusive girls’ school, to which Mrs. Abbott intends to send Kimberly, her fifteen-year-old daughter. Willie, the thirteen-year-old son, is also suffering because his mother won’t allow him to do anything he wants. She insists that he practice on his violin so that she can impress people with her culture.

Well, Grandma is determined to put a stop to all this, so she comes up with the brilliant scheme of inviting the family black sheep, Cousin Oscar, to Mrs. Abbott’s weekend party. She thinks this ought to sufficiently disgrace her social-climbing daughter and set things straight.

This scheme doesn’t come off quite as planned. Since she has never seen Cousin Oscar, Grandma mistakes a criminal for her long-lost relative and he, needing a hideout, accepts her invitation and even brings his wife and daughter along.

Naturally, the weekend party is hardly what Mrs. Abbott had hoped for, but neither is it exactly what Grandma wanted, for the criminal “relatives” find it necessary to get rough, causing plenty of exciting complications. But when Grandma gets hold of her trusty shotgun, she emerges the heroine of the situation; the police nab the long-sought after crooks; Mrs. Abbott begins to see the light, allowing her children to follow their true inclinations; and Brandon and Grandma get handsome rewards. Plenty of twists and turns to keep the audience wondering and laughing.