In ancient Rome, a poster at the Coliseum advertises the Detroit lions in their season opener. A sportscaster describes the scene as Emperor Nero enters the arena in a chariot with tail fins. Nero is a caricature of actor Charles Laughton who played him in 1932's The Sign of the Cross. Nero is to throw out the first victim, but it turns out they are all out of victims. Nero commands Captain of the Guard, Yosemite Sam, to find one or he will be the victim.
Bugs Bunny thinks Sam and his legion marching behind him are a parade and runs up to watch them. They chase Bugs but he trips them. Sam chases him into the Coliseum. As Sam passes the lion cage, Bugs opens its door. After Sam gets away from this mauling, he chases Bugs into another room full of sleeping lions. They tiptoe through this room, but when Bugs climbs out he quickly lowers an alarm clock to wake the lions who maul Sam again. When he gets out this time, he sees Bugs on the other side of a lion pit. He grabs some stilts, but when he's halfway across, Bugs tosses some saws and axes to the lions. As Sam tries to return to safety, his stilts get shorter and shorter and the lions maul him yet again.
Bugs hides behind another door, but instead of opening it, Sam locks it. This was the door to the center of the arena. Sam brags to Nero about finding him a victim and Nero orders the lions to be released. However, the lions run right past Bugs and head for Sam. Sam and Nero climb a nearby column as Bugs dons a laurel wreath and says, "Well, as the Romans say, E Pluribus Uranium". Nero plays Taps on his violin as the lions break down the column.
The lions in this cartoon previously appeared in 1955's Tweety's Circus, also a Freleng short.
When aired on ABC, the part where Yosemite Sam beats the lion ("How many times do I have to tell..you...to....shut.....up?") before realizing that there are no cage bars separating him from the lion was shortened from eight beatings to two.
On CBS, the same scene was edited, but the beatings were cut from eight to one and a half.
On the syndicated Merrie Melodies Show, the same scene was edited, but the beatings were halved from eight to four.
For reasons unknown (possibly time constraints), Cartoon Network's airing cuts out Bugs's line (after Nero and Sam are chased to the top of the column by the lions), "Well, like the Romans say, E. Pluribus Uranium."