The long-awaited day is finally here: Miss Mackle is getting married! The only problem is that she didn't invite any of her Room 3B students to the wedding. The kids don't understand it: a wedding is a time for families to be together, and they are Miss Mackle's Room 3B family - which is important since her father is in the military overseas and won't be home for the wedding. So Harry comes up with a plan to sneak his pals into the wedding ceremony. It seems like the kids are going to make a horrible mess of their teacher's wedding... until Major Mackle shows up just in time!