Ferris Dolan was an extortionist working for Billy Marin.
Dolan and his boys were trying to sabotage a construction site in downtown Gotham. Batman and Robin stopped them and captured Dolan. As he was being interrogated right there, Dolan refused to speak without a lawyer, but Batman showed he was not going to save him unless he got the information he wanted. Though hesitant at first, the prospect of a 30 story drop made Dolan reveal the name of his boss to Batman: a man by the name "Billy Marin". Robin wanted to grill him for more information, but Batman told him get the Batmobile ready as he interrogated Dolan by himself, then leave him for the cops.
Later, Robin searched Dolan's apartment looking for an address of his former boss.