Lon Chaney is known as "The Man of a Thousand Faces," and known for make-up magic and for playing monster parts, but too little is he recognized as a actor -- at least too little in my opinion.
In "The Monster," he is frequently understated and even almost charming, considering the part.
Johnny Arthur, this time, is a star!
This must be his best part and he too showed he is by gosh an actor.
His character changes, with a little chemical help, but he comes across as believable in every characterization. His face, his gestures, his bodily movement are all just perfect.
Turner Classic Movies showed "The Monster" as part of its Halloween line-up in 2016 and as its Sunday night silent on 30 October, although in the Eastern time zone I guess it was actually Monday, 31 October.
It is a treat, at least once, with some funny situations and funny characters, and some generally excellent acting.
There are some directing or at least editing problems, and you can't take the story too seriously, but mostly it is a lot of fun.