Killmer has played Sylvie Brett on the NBC show since 2014.
A brand new episode airs Wednesday, March 10 at 9 p.m. ET/PT on NBC.
ET exclusively debuts a first look from Wednesday's two-hour event, featuring the return of a familiar face.
The two-hour special event kicks off Wednesday, Feb. 26 at 9 p.m. ET/PT on NBC.
ET exclusively debuts a first look from Wednesday's three-hour crossover event.
'They're enjoying each other's company,' Spencer tells ET of the brewing relationship.