The Lost Jungle (1934)

Sharkey, animal handler for the Maitland Circus, is jealous of the success of star animal trainer Clyde Beatty - murderously so, as he has once surreptitiously permitted a hungry lion to be prematurely freed in a cage with Clyde, who escapes being mauled by the skin of his teeth. Far different is his relationship to Ruth Robinson, who is madly in love with him. But just as Clyde is blind to Sharkey's treachery, so he seems dulled to Ruth's feelings for him. When her father, a sea captain, prepares to set sail, he obliges Ruth to come with him if she cannot get an honorable marriage proposal from Clyde; and he is too busy thinking about his animals to notice what she is saying...