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 a staff writer for TV Fanatic. Follow him on Twitter.