Grandpa arranges for Tilda Hicks from Smokey Corners to join the McCoy family as housekeeper, and she immediately sets her cap for widower Luke McCoy. The arrangement proves highly successful until Tilda attends the neighborhood dance with Luke and scores an immediate hit with the local masculine populace.
George MacMichael's big moment during his election as commander of the local VFW post is shattered when Grandpa brings to the ceremonies three of George's buddies who know the real story of his ""heroic"" battlefield actions.
Grandpa becomes involved with diplomatic relations and the U.S. State Department when a foreign nation's farm tour visits neighbor George's ranch and Grandpa pursuades the group to detour by the McCoy farm. At first it appears Grandpa has committed a colossal faux pas, but his apparent blundering develops unexpected consequences.
Grandpa becomes romantically entangled with three matrimonially inclined widows when he encourages their interest just enough to promote some free housecleaning chores and a few well-laundered shirts. Luke and Pepino take a dim view of his scheme when it becomes apparent that the three marriage-minded women are literally doing all the McCoy housework in separate shifts.
Grandpa proves an easy target for Mrs. Gaylord, an ambitious housekeeper who hopes her new position in the McCoy household may lead to a more permanent position for her unmarried daughter. The daughter, Mary, turns out to be an extremely healthy specimen who immediately makes a play for Luke.
Taina Engstrom, a Hollywood actress escaping from her hectic existence, finds peace and quiet at the McCoy farm and discovers that Luke has developed a strong attachment to her. Grandpa grasps the true situation and plans, with Tiana, to prevent Luke from receiving a major disappointment.
Grandpa thinks he has discovered a gold mine in the sky when an Army paratrooper lands with destructive force on a dilapidated chicken coop that was already marked for the scrap heap. When an Army captain arrives to assess the damages, Grandpa paints a black picture. Luke, however, takes a dim view of Grandpa's shenanigans and bluntly tells him so.
The wiles of a smooth-talking saleswoman embroil Luke in a roofing paint swindle that involves several of the McCoys' neighbors. Luke soon finds himself in such an embarrassing predicament that he needs the help of Grandpa to rescue him from it.
Luke feels he has discovered a new source of income when he reports the gossip he overhears at the laundromat to the reporter of the local newspaper and is paid for the items. He runs into trouble with Pat Clemens, who runs a local gas station, when he reports that Pat is getting married.
Afraid that Grandpa will disapprove, Luke pretends that the girl veterinarian secretly treating their ailing cow is one of his new girlfriends. When Grandpa learns that Luke's ""romance"" is actually only trying to cure Agnes, the sick cow, he explodes, ordering the girl off his property.
Grandpa and Luke are left with an unproductive hired helper when Pepino apparently inherits a valuable Arizona estate. He warms up his romance with an old girlfriend and brings a flood of salesmen to his doorstep.
Uncle Rightly McCoy starts courting Flora, hoping she will finance his musical milker. When Luke informs George that Uncle Rightly is only interested in Flora's money, they decide to step in and break up the romance. Their scheme doesn't quite work out as they had planned.
Grandpa and George take turns at playing Cupid when their respective farmhands, Pepino and Pedro, find themselves competing for the same girl. Grandpa steps into the romantic triangle because it turns out that Pepino's working efficiency suffers as he loses favor with his girlfriend, Chiquita.
Luke lands the enjoyable job of teaching calisthenics at a ladies' health club. Grandpa decides that Luke's presence there may attract some business for the McCoy roadside fruit stand. Grandpa then surreptitiously tempts the dieting health club enrollees with a variety of tasty fruit products, thus undermining the efforts of unsuspecting Luke.
Luke is horrified when Uncle Rightly promotes a corn growing contest at the Grange and is so carried away he volunteers a $500 award to the winner in Grandpa and Luke's name. When Luke learns Uncle Rightly doesn't have the $500, it becomes a major problem of raising the money and saving face with the Grange members, but Rightly solves the problem in an unusual way and comes up with the prize money.
A winsome dance instructor tricks Luke into signing up for a 20-year dance course. It is up to Grandpa to rescue him from this embarrassing situation with a devious plan that involves Grandpa's signing up for the course, too. He also saves George, who likewise was tricked into taking the course.
Luke gets a hair-raising ride in an airplane that leaves him dizzy when he tangles with a crop duster over the affections of a wealthy girl from Texas, and winds up on the short end.
Grandpa bristles at Sir Fergus, head of the Scottish branch of the McCoy family, when he arrives and proceeds to exercise all the authority of the Laird of the Clan. Grandpa's anger erupts when Sir Fergus extends his influence to Grandpa's pet goose, Floyd. Grandpa begins one of his devious plots to oust the Scotch usurper from his position of power.
Luke and Louise feel they have a real problem with Greg, who is addicted to telling fantastic stories about imaginable playmates and people. When they return home from a day's outing, after leaving Greg with Pepino, he tells them three escaped convicts had been captured by the police at their home, and they decide it is just another one of his tall tales.
Luke discovers a new romance when he meets an attractive widow, Louise Howard, after her runaway cow tramples the McCoy cornfield. Grandpa connives to promote a romance between Luke and Louise in a most surprising way.