Once again it's all about chemistry in this second season of Rizzoli & Isles (with 15 episodes, plus bonus material, on three discs). Sometimes that's literally the chemicals used by Dr. Maura Isles (Sasha Alexander), the forensic pathologist who, as medical examiner, figures out what killed the victims whose murderers Boston detective Jane Rizzoli (Angie Harmon) is trying to bring to justice. More often, it's the chemistry between the two title characters that's at the heart of this series. This pair is a younger, much sexier, distaff answer to The Odd Couple, with Isles the meticulous, sometimes prissy Felix to Rizzoli's less analytical, more cynical Oscar. They're both good at their jobs, of course; Isles's knowledge about just about everything is almost laughably encyclopedic, while Rizzoli is an intuitive, courageous cop. But though the procedural aspect of the show is detailed and reasonably involving (this season they deal with vicious rapes, fire bombings, and ice pick killings; there are also fairly preposterous episodes involving a modern-day witch hunt, a baseball star run amok, a So You Think You Can Dance-type competition, and more), it's the constant banter between these two mismatched best friends that fuels the episodes. They talk about man issues; Maura's hot but naive, Rizzoli's skeptical, and both are single. And they have family issues--boy, do they have family issues, what with Jane's mother (Lorraine Bracco) in extreme bitter mode over her impending divorce and her wayward youngest brother having just been released from prison (her other brother's a cop), while Maura's biological dad is a notorious mobster who long ago somehow hooked up with her beautiful socialite mother, played by Jacqueline Bisset. Much of this is presented with an appealing light touch. Notwithstanding some gruesome cases, Rizzoli & Isles is not a gritty show; in fact, there's enough cutesy stuff, even when they're on the job, to