Question: Which character in Harry Potter and the Prisoner of Azkaban helped Harry rescue Hermione Granger from a troll?
Sentence (from "Harry Potter and the Prisoner of Azkaban"): Along with friends Ronald Weasley and Hermione Granger, Harry investigates Sirius Black, an escaped prisoner from Azkaban who they believe is one of Lord Voldemort's old allies.
Relevant evidence: Yes