Artist Paul Dover helps his blackmailed sister Ellen retrieve compromising letters by tracking a shipment to LA, aided by his guide dog Ace, while fending off a criminal gang.

Paul Dover lives in Paris and works as an artist. He is visited by Julia Fraser an art buyer and critic who irritates Dover with her opinionated attitude. When she finally finds a piece of sculpture that she likes, he quotes a ridiculously high price which she refuses, but she is very intrigued with him and at least she leaves on a friendly note. But Paul's treatment of Julia is not usual for him. Earlier he had received an upsetting visit from his kid sister Ellen. She is married to a very wealthy man who is running for office and who, although he is in love with his wife, will not bear any scandal. Unfortunately, we learn, she is being blackmailed by a man who was her fiancé before she married her husband. She discovered him to be a cad, and she broke off the relationship. But he had saved her love letters to him, and now is demanding two hundred thousand francs from her or else he will publish her letters. She asks Paul to help, and he agrees. The result is that the letters end up packed in a shipment going to the Los Angeles Art Museum. Paul determines to get them, and along the way he ends up on the wrong side of a criminal gang's intentions, and has to pose as being blind. This was RKO's method of introducing Ace, the Wonder Dog, their answer to Rin-Tin-Tin, who becomes Paul's seeing eye dog. Can Paul, with the help of Ace track down the letters, fight off the gang and save his sister's marriage?—Jim Knoppow