Sylvester is aghast when he sees that his son is fraternizing with (of all possible creatures) a blue jay by the name of Spike. Through his natural feline instincts, he does everything in his power to not only destroy this relationship, but destroy Spike as well.
I always found the earlier Sylvester/Sylvester Jr. cartoons to be more enjoyable than the later ones. In the earlier cartoons, Sylvester Jr. was quite sassy and straight-up compared to his more innocent persona of the late 50s and early 60s shorts. As such, they had quite a bit more spark. Unfortunately, this cartoon falls victim to being one of the latter shorts. Essentially, it is a Sylvester/Tweety cartoon with Tweety being replaced by the similar but less interesting Spike (who not only talks in whistles but also has that same "cute/innocent on the outside but sly and crafty on the inside" personality - albeit to less funny effect) and Sylvester Jr. simply standing there and watching. Save for may be the final gag, none of the jokes here are too terribly imaginative or funny, and the ending is too vague to really work as a punchline.
Overall, this is by no means a bad cartoon. It is, however, a clear example of the WB cartoon studio running out of creative steam, which of course lead to the closing of the studio just three years later.