S4, E17: Hanna's new interest in crime novels helps her to come up with a plan to try and figure out whose body is in Ali's grave. While Hanna is on her hunt, Spencer is working overtime to decipher the stories in Ali's diary which she hopes will reveal the identity of Ali's mystery man. But with both girls hot on the trail, will their work lead them straight into the path of "A"? Meanwhile, Aria is upset with the new friend Mike (recurring guest star CODY ALLEN CHRISTIAN) has made and Emily's dad (recurring guest star ERIC STEINBERG) is concerned about her behavior.