My Three Sons (1960)

S6E5 There's a What in the Attic?

In the middle of the night, an escaped lion from the circus wanders into the Douglas home, startling Ernie, who rushes to wake the understandably doubtful Steve. Despite his skepticism, Steve joins his new stepson for a closer look. When Steve finally spots the lion, he finds himself nervously engaged in a game of tag with the creature, urging the family to keep their bedroom doors shut for safety.