EXCLUSIVE: 'Younger' Star Debi Mazar Makes a Splashy Debut on 'Elementary' -- Watch!

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is getting Younger.

The CBS detective drama welcomes Younger star Debi Mazar on Sunday’s episode titled “It Serves You Right to Suffer,” and only ET has the exclusive sneak peek at the Aidan Qiunn-directed installment.

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In the clip, Mazar’s Detective Cosa questions Sherlock Holmes (Jonny Lee Miller) and Joan Watson (Lucy Liu) as they inquire about the murder of a gang member. Detective Cosa is immediately interested in why a seemingly cut-and-dried case has caught the interest of Sherlock and Joan.

Sherlock deduces that the murder is quite unusual, though unforeseen (and rather conspicuously timed) incidents are threatening to muck up the standard timeline for the investigation.

“What exactly is Major Case’s interest here? Isn’t a dead gang banger a little, like, straightforward for you guys?” Detective Cosa asks pointedly. “Slow week,” Sherlock quips.

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Turns out, there is a reason for their investigation. Sherlock and Joan’s pal Shinwell Johnson (Nelsan Ellis), a former drug dealer, is being framed for the murder. Watch the scene above to see how it all plays out.

airs Sundays at 10 p.m. ET/PT on CBS.