The Great Louse Detective (S14, E06-297)

You can tell by that face that Bob just wasn't into killing Bart.

Plot Summary
The Simpsons are invited for a free day at the spa.  There, Homer partakes in a steam room; when he's by himself, an unknown person locks Homer inside in an attempt to kill him, though Homer is able to escape in time.  He goes to the police to report the attempt on his life, and Chief Wiggum decides that in order to catch this killer, Homer needs the help of someone with the mind of a criminal.  For some reason, Wiggum chooses Bart's pal Sideshow Bob for this.

Bob agrees to help find Homer's assailant in exchange for having first pick in an upcoming prison play.  Bob is forced to wear a shock collar so he doesn't try anything silly like escaping or killing Bart.  As Bob begins to investigate by following Homer's movements, Homer crashes his car and chides a mechanic, Junior, just because.  Bob quickly learns that Homer has a lot of enemies.  To further that point, Bob sets up a dummy of Homer outside, which is attacked by said enemies, and thus Bob is no closer to figuring out the killer.  Bob does start finding clues, such as a thumbprint smudge on the spa postcard sent to the family, but as Bob advises Homer to stay out of sight, Homer learns he's been declared "King of Mardi Gras" (likely because the killer stuffed votes for him at the poll), and is forced to be out in the open for a significant period of time.

At the parade, Bob learns that the float Homer is riding was 'tuned up' by a mechanic.  Bob quickly adds up the pieces and realizes that Junior (and somehow not any other mechanic) must be the murderer.  The float Homer is on has had its brake lines cut, and sure enough the float goes down a hill.  Bob acts quickly to save Homer's life, and the two spot the murderer and give chase.  Cornering him in an alley, the murderer reveals himself to be Frank Grimes Jr., the son of Frank Grimes, who died after Homer drove him insane but apparently not before makin' babies with prostitutes.  The police arrive to arrest Junior and to tranquilize Bob, his job now done.

That night, Bart is visited by Bob, who had escaped the police, and attempts to kill Bart quickly (as per Lenny's advice earlier on), but finds that he can not kill Bart, having become accustomed to his face (singing a song stating as such).  Bob takes his leave, but not before getting shocked once or twice or several times more.

Quick Review
As far as Sideshow Bob episodes go, its the weakest entry thus far, slightly worse than Krusty Gets Busted, but as far as Season 14 episodes go its the highlight thus far.  Kinda sad to think about either way.  The episode itself had a good quantity of jokes, with Bob once again leading the humor charge.  Though, the reveal of the murderer was underwhelming, given age discrepancies of the two Grimes and the odd reference to Homer's Enemy, it just felt odd.  Still, I ended up enjoying the episode which, given how the season has gone thus far, is a compliment.

Final Score: 7.8