With Burgess bleeding out in the street, Roman enters the house and finds a dead body and a lot of traps. The body turns out to be a professors son. We also find out his wife has went missing. He filed a restraining order against a former student who took an unnatural interest in him when he wanted him to be his father. This could stem from him not having a father. 

Lindsey assisted on the case before starting her new job on the task force. 

Platt visits Burgess in the hospital and has a conversation with Ruzek and says some funny things to him. 

Halstead finds a telephone number on Spencer after the team catches him. He rings it and it's disconnected. The team find the wife at one of her homes she sold with a bomb attached to her. Halstead and Voight attempt to disarm it. It was activated when Halstead phoned it. They manage to disarm it with just seconds to spare. 

Voight visits Burgess and offers her Lindsey's old job, but will she take it?

Burgess and Ruzek tell each other they love each other, while Ruzek informs Burgess he was very worried about her when she got shot.