Ruzek goes undercover on a robbery, but it doesn't go as planned when his mark Frank drives his truck into a restaurant and shoots someone.
Lindsay and Halstead interview the store owners who were robbed.
Roman requests a few days off to recover from his bone marrow donation.
Ruzek is being investigated, but Voight sticks up for him.
Lindsay and Halstead try to track down Ruzek's CI, Jesse. They arrest him and question him about Frank. They want him to help them find Frank.
Lindsay and Halstead question Frank's parole officer. He gives them the number of his job at a graveyard. Atwater and Olinsky find out he only worked one shift and had someone punch in and out for him.
Lindsay and Halstead find Jesse dead. Ruzek feels guilty.
They find a connection to the murdered woman's son to a pet store. Atwater and Olinsky question the pet store owner on Frank.
Lindsay, Halstead, and Dawson follow a lead to a hotel. Halstead and Dawson chase down and arrest Frank. Lindsay questions the son on the robbery and he tells her no one was supposed to get hurt.
Roman learns the boy is not healthy enough for the transplant.
Halstead helps Lindsay move in a new couch and they get back together.
Ruzek learns he'll be stripped of his police powers until the Chief determines his future.