Olivia Benson (Mariska Hargitay) has faced her fair share of tough cases on Law & Order: Special Victims Unit but this week's episode presents a different kind of challenge.

In a sneak peek at tonight's tense episode, she must help an elderly victim (guest star Fionnula Flanagan) with Alzheimer's who has a bit of trouble picking out the man who assaulted her from a lineup. As the suspect's lawyer points out, Benson faces an uphill battle with this sensitive case.

"Even if she picked him out, it wouldn't stand up in court," he notes in the video.

While the victim's testimony might be weak, it's still a bad idea to underestimate Benson. As we've seen over the course of 19 seasons, Benson can accomplish pretty much anything once she sets her mind to it. Her lengthy arrest record can certainly attest to that.

Wednesday's episode will also be a big one for Fin (Ice-T) who will finally receive his sergeant orders. After putting it off for years, he's taking a huge step in his career and that could mean big changes for the SVU family.

Find out how it all goes down when Law & Order: SVU airs Wednesday at 9/8c on NBC.

Mariska Hargitay, Law & Order: Special Victims UnitMariska Hargitay, Law & Order: Special Victims Unit