This review contains MODERATE SPOILERS. At least we think it does. Also it was edited by several people so there may be variations in style.
They are all trying to MURRRDURRR mEEEEEh
The episode opens on a dark shadowy figure being all dark and shadowy in the dark shadows
Now that we're onto episode 3, it seems we've fallen into the familiar Naruto practice of introducing a new character and their backstory in each episode. Here, we meet Metal Lee, Rock Lee's son, who appeared in previous episodes as well but was not yet properly introduced. Metal, aside from having a seriously badass name, is skilled with taijutsu like his father, but has performance issues when he's nervous. He will at such times make mistakes which prove comedic and/or result in substantial property damage.
Side note: why is it that no character seems to have new abilities? Boruto, Shikadai, Inojin, Metal... their go-to techniques are all the same as their fathers'. I mean, it makes sense that these are passed down in the family, but currently it makes the plot a little boring as we're already familiar with what they can do. Hopefully we see some original moves soon.
Anyway, during a training session Boruto mindlessly throws a deadly weapon he STOLE from someone else's locker at a bunch of students, proving yet again that he's either an idiot or genuinely doesn't care about potentially killing someone. Yes, in addition to terrorism, truancy, theft, laziness, and jackassery, we add attempted murder to Boruto's rap sheet.
Shino, the teacher, reprimands the deadly assault by assigning some community service to Boruto. For some reason, Inojin, Shikadai, Metal, Iwabe, and the class rep (have they even said her name yet?) all have to take part in Boruto's punishment, which is to help mend Naruto's face on Hokage Rock. WHICH BORUTO DESTROYED IN THE FIRST PLACE. Konoha is probably like South Park, they are pretty much used to their town getting destroyed every other week.
While the other kids (sans the class rep) are dicking about on the job, Metal gets anxious about working on such an important monument and ends up causing more of Naruto's face to collapse. Somehow there are no negative consequences to this act and the kids are simply sent home. Walking back together, while discussing where they should sup, Metal lags behind and keeps muttering apologies and regrets to himself. Shikadai gets fed up with him being a whiney bitch and tells him that he should get his act together or he'll just keep sucking forever (in essence). Metal, being a delicate flower, runs off crying.
There follows a scene at the Nara homestead (their apartment/townhouse really) where Temari, now a stay at home waifu, chews off Shikadai for letting himself get dragged into trouble at school. Shikamaru however provides insightful advice which makes Shikadai realize he was too hard on Metal and he shouldn't go off judging others. It was kind of a beautiful moment which was immediately ruined by Temari who just doesn't get it. T'was funny though.
The next day, Shikadai tries to apologize but is met with a merciless, confident Metal who is in full control of his abilities and looking for a murderous connection. In a monster of the week twist, it turns out that the dark chakra that afflicted Denki in episode 1 has now taken hold over Metal. We assume that this recipe will repeat itself a few more times.
Shikadai has to enlist Inojin and Boruto's help to bring Metal down. Again, Boruto notices the dark chakra with his doujutsu, but realizes no one else can see it. After the dark chakra leaves when Metal is knocked out, the boys sit around playing video games together, presumably bonding over the recent reciprocal murder attempts.
Back at home, Boruto asks Hinata about her Byakugan and wonders if chakra is what he's been seeing... when she asks what prompted his inquiry, he doesn't tell her what's been happening. Because why would you try to figure out what's possessing your peers into trying to kill you and/or others?
P.S. Based on the pattern of the first and third episodes and the previews for the next episode, it seems like next time is Sarada's turn to be possessed by the ghost of emos past.