Why did Nicole hate Ruzek?
That was a key question on Chicago PD Season 4 Episode 18 when Burgess's sister arrived in town for a visit and quickly caused a stir.
Did Burgess manage to calm things down?
Meanwhile, someone was murdered over a piece of mysterious footage, prompting the team to uncover details that painted one of Chicago's wealthiest families in a bad light.
Were they really as evil as they were made out to be?
Use the video above to watch Chicago PD online to get caught up.
Paul Dailly is the Associate Editor for TV Fanatic. Follow him on Twitter.