When Officer Steve Tomlin was killed on the job, Danny and the rest of the precinct left no stone unturned to find his killer, only they uncovered more than they bargained for in Blue Bloods Season 4 Episode 21.

Turned out Officer Tomlin not only had a wife and two college aged daughters but also a secret girlfrined and new baby. When his wife found a phone number in his pocket, she called it thinking she was yelling at the girlfriend.

Unfortunately the number was to the drug dealer in Steve's undercover operation and his wife's tirade about being married to a cop is what got him killed.

Meanwhile, Nicky gets help from Jamie and Erin to find a classmate she thinks is living on the street. But Tyler isn't a junkie as she suspected. He's searching for his mother who is. 

You can watch Blue Bloods online any time here at TV Fanatic. 

Watch Blue Bloods Season 4 Episode 21 Online

C. Orlando was a TV Fanatic Staff Writer. Follow her on Twitter.