Harper's Island, the guiltiest pleasure of the 2009 summer TV season, is part Agatha Christie and part Friday the 13th. This cleverly plotted 13-episode CBS mystery event invites return visits to the eponymous island where a good portion of an ill-fated wedding party will not survive to celebrate the happy couple's first anniversary. Harper's Island begins with a "Whap" and goes out with a "Sigh" (each onomatopeaic episode title replicates the sound of a victim's demise). Here's the set-up: Pauper Henry (Christopher Gorham) and princess "Trish" (Katie Cassidy) have invited family and friends to Harper's Island, located 37 miles off the coast of Seattle, for their nuptials. Seven years earlier, John Wakefield slaughtered six people there. These were the first murders in the history of the island. A title card warns us they will not be the last. One by one, episode by episode, a killer (or killers) methodically picks off the wedding guests in grisly and gory fashion. Some characters are more expendable than others, and those who are dispatched early don't get the chance to make much of an impression (cousin Ben doesn't even make it out of the dock in the opening episode), but as the mystery unfolds and the body count escalates, viewers become more emotionally invested in those who survive the longest. For Abby Mills (Elaine Cassidy) this is all kinds of personal. Abby, Henry's once-inseparable childhood friend, has not been back to the island since Wakefield, presumed dead, slaughtered her mother. She is reunited with her estranged father, the sheriff (Jim Beaver), and Jimmy (C.J. Thomason), the boy she left behind. Harper's Island will keep viewers guessing until its final twist, which is a doozy, although somewhat suspect. But until then, the series is an effective horror show that gets under your skin with its attractive cast, soap-opera dramatics, tantalizing red herrings, and quality kills (although nothing in the show is as creepy as the unnerving little girl named Madison). Those who missed the boat when Harper's Island first aired are advised to steer clear of the spoiler-heavy bonus features until you've watched it through to the bloody end. --Donald Liebenson