Their Mutual Friend (1913)

Disgusted by the unsanitary conditions of the flat in which she lives, Patty Gordon, a pretty young artist, writes anonymously to John Richardson, asking him to investigate the conditions of his tenements. Plainly dressed, Richardson goes down to the tenements and rents an apartment for himself, so that he may see firsthand whether or not there is cause for complaint. He is accompanied by his dog, Dick, a valuable thoroughbred collie, who, seeing Patty's door open, enters and makes friends with her.