Oh, oh! It sounds like there's a change coming.

Marcus was looking ahead to his future which seems to be leading to breaking up the old gang on Elementary Season 6 Episode 12.

How did this all come about? Blame Sherlock. That's usually a safe bet.

Actually, Sherlock was only being nice when he set the U.S. Marshal's Service on Marcus' tail.

That's really better than it sounds. Sherlock used his connections to get Marcus recruited.

 Sherlock respected Marcus's abilities as a detective. So now he was trying to put Marcus on a career path that would challenge him more than his current role.

Related: Elementary Season 6 Episode 11 Review: You've Come a Long Way, Baby

Let's face it. Sherlock does suck all the air out of a room. There isn't much opportunity for a young detective to grow around him. Joan is the exception.

It's not Sherlock's fault. He's just that good.

So for Marcus to escape sidekick status, he's going to have to leave, to find a place he can make his own.

He had all the personal reasons in the world to stay. His mom was there, and Chantal was there.

Face it, his mom just isn't going to be happy about her son leaving town. But Chantal seemed amenable to a change in scenery. Lawyers can find work in any city where there are Marshals offices, so that isn't an issue.

Marcus also felt that applying would be a betrayal of Captain Gregson, the man who taught him how to become a detective.

Fortunately, his mentor gave Marcus his blessing, although he certainly wasn't pushing him out the door. That gave Marcus a clear conscience to apply.

Related: Watch Elementary Online: Season 6 Episode 11

Is it a done deal? Is Marcus gone in six months (in other words, Elementary Season 7?) Although the powers that be could concoct some way out of that path over the second half of Elementary Season 6, I think Marcus will be gone.

This would mark the first change in the core lineup in six seasons. Elementary has had a formula that works, shuffling recurring characters in and out through the years, some from the Sherlock mythos, some not.

If one of the big four has to go, Marcus would be the logical choice. Now his replacement can be worked in, someone younger and greener and likely female. It could lend the series some dramatic tension which isn't present in the current comfortable arrangement.

So let's just enjoy Marcus for however long he's there, and worry about future changes when they happen.

Now back to the case of the week, which had its share of enjoyable twists and turns.

Related: 13 Notable Male Roles Rewritten as Amazing Women

Maria, the missing woman, whose apartment Joan found ridiculously easy, was a financial dominatrix, who humiliates men for gift cards. OK. That's different. And untraceable.

Oh, yeah. She also makes toys, which she markets herself. That's an interesting dichotomy.

It made sense that Sherlock and company would track who she may have pissed off enough that he would kidnap her. There was no doubt it was a male.

And their main suspect-turned-lead was a would-be mass shooter they located through a website for the involuntarily celibate (what a fancy term for misogynistic losers,) who is in love with her. I guess help is help, whatever the source.

He revealed that Maria had just gotten back from the cross-country tour, which Joan figured out what to promote her toy line. 

Didn't Sherlock seem a little peeved about the geeks at the convention? At least it gave them another suspect-turned-victim, Roman, who, it turned out, was also missing and was Maria's boyfriend.

Related: Get CBS All Access via Amazon Channels for Hit Shows, Exclusive Originals & Live TV! 

That's when I thought everything took a hard right.

Although Maria was involved, it was Roman, the blacksmith, who was the target of a Latino gang, and they were both taken, so they could train new people to forge guns for the gang.

As usual, it was an obscure, barely seen character who blew things wide open, in this case, Maria's brother, who was also a member of that gang. He cracked during interrogation, and Maria and Roman were rescued. They were never seen, mind you, but did that really matter?

No, the whole case was wrapped up rather abruptly to allow extra time for more deliberation by Marcus. Was anybody at all surprised at the ending?

SPOILER ALERT: It's back to Joan's quest for a child on Elementary Season 6 Episode 13, as it's time for a home visit by her caseworker. It's time to send Sherlock to the movies!

To follow this season's developments, watch Elementary online.

Are you surprised Marcus is leaving? Who will that affect the most? How did you like the case of the week? Comment below.

Dale McGarrigle is a staff writer for TV Fanatic. Follow him on X.