In the 1930s and 40s, Mountie movies were very popular and Hollywood churned out a ton of them. Nearly all of them were B-pictures, though a few (such as "Rose Marie" and "Suzannah of the Mounties") were A-pictures...with large budgets, longer running times and A-list stars. "Heart of the North" is an odd one, as it sure looks and feels like a B, but Warner Brothers gave it the A-picture treatment by extending its length and filming it in Technicolor...something they'd NEVER do with a B. Oddly, however, the actors are pretty much who you'd expect to see in Bs...particularly Foran who made a ton of western Bs during this era.
Soon after the story begins, you are introduced to a Mountie and his unnaturally adorable little girl (Janet Chapmin). Since he is NOT the star of the film, you know that soon he'll assume room temperature...especially since the girl also loves another Mountie she calls 'Uncle' (Dick Foran)! The rest of the story consists of the Mounties trying to catch up with the murderers and deliver justice...and with the help of an incredibly smart German Shepherd (something OFTEN seen in Mountie films).
As far as Chapmin goes, she is an incredibly talented actress for a 5-6 year-old. She also is so cute and perfect that you'll either love her or see her as a walking, talking sack of sugar! I do think she was better at acting than one or two of the adults in this film...but I don't want to be mean so I'll not mention who. Foran plays a typical western sort of part except he doesn't sing at all! As for the rest, there are a lot of familiar Warner character actors (such as Allen Jenkins).
In many ways, this movie is a B. The plot is full of the usual cliches and stars B actors....and the story is very similar to many other Bs I've seen. But, somehow, it was done in color and is longer than B-length. I'd consider it a B+ movie...or perhaps an A-....and about as entertaining as a B. Overall, I think it earns a 6...entertaining but not exactly a must-see film.
