What is the last name of the late-night mentor?
Josh and Dinah Barkley (Fred Astaire and Ginger Rogers) are a husband-and-wife musical comedy team at the peak of their careers. After finishing a new show, Dinah meets serious French playwright Jacques Pierre Barredout, who suggests that Dinah should take up dramatic acting. Dinah tries to keep the suggestion a secret from Josh, but when he finally discovers Dinah hiding a script for Jacques' new show from him, the couple splits up.  
Their good friend, acerbic composer Ezra Miller tries to trick them back together again, but fails.  When Josh secretly watches Dinah's rehearsals for Barredout's new play and sees how she is struggling, he calls her up and pretends to be the Frenchman, giving her notes that help her to understand her part, the young Sarah Bernhardt. As the result, Dinah gives a brilliant performance. After the show, she accidentally learns that her late-night mentor was Josh and not Barredout, so she rushes to Josh's apartment and the two reconcile.
Barkley