I knew this film had a reputation as a brutal shocker, but I was stunned by how nasty the violence is in Behind the Door (1919)! Far superior to most WWI-thrillers of the period, which were more interested in conveying propaganda than telling a story, Behind the Door is best described as a revenge tragedy.

We see no blood or guts spilled, nor do we see every detail of the awful fate of Oscar Kruger's beloved wife Alice, but what we do see is more than enough to disgust. And the way Oscar takes his revenge will have you thinking of the ending of The Black Cat (1934),only in this film, the vengeance is better presented, with far greater horror and pathos, in my opinion-- and I say this as a major fan of The Black Cat.

The best part of the movie is the character of Oscar, brought to life by Hobart Boswarth. While he goes a little overboard at times, he sells the character's arc so well. Oscar starts out as this sweet, loving man who, by greater degrees as the movie progresses, is forced into savagery and violence by the intolerant small-town hotheads who view his German ancestry as akin to treason and by the German U-boat crew who brutalize his wife and leave him for dead.

The cinematography is stunning, even gothic at times without steeping too far into expressionism.

Not to be missed if you love silent films! Heck, not to be missed if you're still under the delusion that the silent era was some kind of age of innocence.

One cannot say there weren't any flaws in either the plot or production - among them, the blatant fact the Bosworth is way too old for his leading role, to be too convincing (he was in between 51 and 52, when this was shot!) - the first time you realize how wrinkly both his face and hands are, I'm sure you'll agree with me! Not that being old is a fault on its own right, it's just that we end up feeling the rather heroic role cries out for a younger thespian, no doubt about it.

Also, as I seasoned photographer, I feel the "restored" print (a restoration apparently endorsed by The Library of Congress) could have been, well, more properly restored: on some scenes where the celluloid stuck for many consecutive frames and decay is quite obvious, I feel they missed on the opportunity to simply pick the best frames where some still scenery was not affected by it and simply clone it, just like we photographers do to photographs where there are good and bad ones in a series! When I have the time, I'm going to open some of these frames on Photoshop and intend to prove this theory of mine! But back to the film itself, I found it a touch of genius of how, only in the end we come across the reason for the title (I was starting to wonder if it would ever show up) - very clever indeed - and scary too! Hence my dutifully adding "Thriller" to its genre which, by the time I wrote this, was absent from this IMDb entry.