The title is a typical play on words for "heir," and although it suggests a mystery story, it bears no apparent relationship to the plotline.
A magician named Ala Bahma is nailing self-promoting posters on every conceivable surface... including, as it turns out, a tree in which Bugs is living (apparently having moved from his "underground" home to a "high-rise"). He protests having his home encroached, proclaiming that "there's still such a thing as private property, you know". He begins to continue the protest until the magician apologizes and asks Bugs if he likes blackberry pie (this is one of the many non-carrot foods that Bugs devours). The bunny's expression changes to joy for the moment, as Ala Bahma produces a pie from under a "magic" cloth... until he splatters it in his face, walking away and ridiculing the rabbit. We cut to a closeup of Bugs, with pie-filling and bits of crust dripping down his face, calmly facing the camera, and invokes the time-honored Warner Bros. homage to the Marx Brothers: "Of course, you realize this means war!"
The rabbit spends the rest of the movie at the theater where Ala Bahma is performing, wreaking havoc during his prestidigitations (although the magician sounds like fellow cartoon star Porky Pig when he tries to say that word; Bugs later does this as well). In a climactic moment, he thinks he has blown Bugs away with a shotgun. Instead, Bugs pops out of the magic hat and awards him a cigar... which promptly explodes in his face and stuns him. In a delicious bit of revenge, Bugs produces a pie from under a magic cloth. He says to the audience, quoting Red Skelton's "Mean Widdle Kid", "If I dood it, I dit a whippin'... I DOOD IT!" and splatters the pie in Ala Bahma's face. Bugs then sings "Aloha `Oe" on a ukulele as he descends into the hat and the cartoon irises out.
DVD - Looney Tunes Golden Collection: Volume 3, Disc One (with optional commentary by Greg Ford)
This is the first cartoon Bugs quoted the famous Groucho Marx line, "Of course you realize this means war!".
It is one of the few cartoons where Bugs doesn't say "Eh, what's up, Doc?".
When this cartoon aired on TBS (back when TBS and TNT aired classic cartoons, mostly from the pre-1948 package, as other channels had rights to the post-1948 package), the beginning establishing shot showing posters for Ala Bama's show plastered all over walls, fences, and trees was cut (most likely a time cut, as there is nothing objectionable about the scene).