Mammy has a grandson she adores even though he is a good for nothing. One day Maurice disappears and Mammy becomes blind. When Maurice finally announces his return the fond old lady is overjoyed. Unfortunately, Maurice's plane crashes and catches fire. The young man is reported missing, presumably dead. Pierre, Mammy's husband, can't bring himself to announce such a shocking news. Desperate, he finds no other solution than subterfuge : he will ask a young couple to pass themselves off as Maurice and his girlfriend...