The letter said in part "We do not propose to make any more pictures with Rin Tin Tin appearing therein.  It has been decided that since the talking pictures have come into their own, particularly with this organization, that the making of any animal pictures, such as we have in the past with Rin Tin Tin, is not keeping with the policy that has been adopted by us for talking pictures, very obviously, of course, because dogs don't talk."

June plays the (innocent) daughter of a gold miner who is ambushed and killed while returning from his secret mine.  Rin-Tin-Tin knows who killed the fellow, but even though Rinty keeps attacking the killer throughout the movie, it takes twelve excruciating chapters before anybody other than the dog figures it all out.

Add to the poor plot a whole lot of eavesdropping (one guy even hid in the fireplace), some implausible chapter endings, horrible acting, and the fact that most of the film was shot silent with voices and sound effects dubbed in later and you really do have a case for making The Lone Defender the worst serial ever made.

June throughout shows the fact that she lacked any proper training for voice characterization.  She was, of course, lovely to look at, rode her horse better than anyone else in the film, and handled the action scenes with aplomb.  But when she had to emote, the stiffness and timidity showed through.  It was not totally her fault.  Whenever the script, or whatever they actually used for a script, called for her to speak any kind of dialogue, the dialogue was so poorly written they might just as well have had June speak German or have Rin-Tin-Tin say the lines.

Her brother Louis summed it up to Scott Johnson by calling The Lone Defender "..a miserable job."  I'll drink to that.  I'll need to if I ever have to watch this one again.