has marked with an emotional five-act installment that dove deep into Detective Olivia Benson's past and, of course, featured the crime drama's characteristic twists and turns.

Olivia, played by , had a flashback at the start of Thursday's episode to a dinner she had with her late mom, Serena, during season 9. During the dinner, Serena asks Olivia to leave behind her job with the Special Victims Unit.

Olivia has a complicated history with Serena, who became an alcoholic after she was raped and got pregnant with Olivia. The flashback marked the first of many familiar faces fans, and Olivia, saw throughout the episode.

When she arrived at the station after dropping son Noah off at school, she was surprised to find her old partner, Nick Amaro (), waiting for her in the interrogation room. Nick served at SVU for several seasons before the actor's departure in 2015.

"You're a captain now, you don't like surprises?" he teased Olivia, who joked, "I've never liked surprises."

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