Megan Flynn's brother Sean has been convicted of a horrible murder. She knows he's innocent, but can't prove it. He's been sentenced to death and is done appealing his sentence. Megan can't accept that her brother is going to die for a crime he didn't commit, and is determined to save him.Cole Williams is a cop - the cop who arrested Megan's brother for murder. He and Megan had been dating at the time, and after the arrest their relationship ended after it was made public. He's been called out to investigate a brutal rape and murder. He's surprised when he gets to the crime scene and Megan is there - she's the teenage witness' legal advocate.After Megan notices a similarity in the current murder and the murder her brother was convicted of, she asks Cole for his help. He doesn't want to help, but once Megan starts uncovering clues, he's not only helping her find the truth, he's helping her stay alive.My thoughts:Megan is a likable heroine, even with her single-minded determination to free her brother. Cole is a by-the-book cop; noble and courageous, if lonely. Even though he believes Sean is guilty, he agrees to help Megan, if only to help her accept the truth. I liked Cole and his ability to admit to himself that this might be his second chance at happiness, however briefly. We don't really get an in-depth look at either the hero or heroines pasts though, only that Megan and Sean's parents died when they were young.The killer was cold and calculating, and entirely insane. At first I wondered how Megan was connected, but as we are given glimpses of his history, we see his path to insanity and why he does what he does. I pegged who the killer was early on, but there were a few spots in the story where I second-guessed myself.I like Jami Alden's writing style, she has an ability to pull the reader into the scene without being overly descriptive. For example, during scenes in a trailer park, I could picture it in my head, the dirt, the desperation, the hopelessness of the residents. The climax was fast-paced and full of suspense. Beg for Mercy was a quick and entertaining read.