As the third season of Rizzoli & Isles came to an end, Jane tried to convince Casey, not to participate in a potentially life-threatening surgery, and Maura agreed to donate her kidney to save her half-sister, Cailin.
Meanwhile, Jane?s brother Tommy and Frost were recovering from injuries they incurred while being trapped during a building collapse.
This season, Jane and Maura will investigate a number of complex and troublesome cases, including a deadly shooting at a community parade, the brutal killing of an overzealous journalism student and the pending murder trial of Maura?s biological father, Paddy Doyle (guest star John Doman ? Damages, The Wire).
In the season four premiere, a community parade turns deadly in a case that brings family tensions and politics to the forefront. Maura, who is dealing with her own family issues, is not quite herself. And a surprise visit from Lt. Col. Casey Jones reveals some shocking news.
Guest stars in the fourth season also include Amaury Nolasco (Prison Break, Transformers) as the newly appointed head of the Boston Police Department?s drug unit, who has a painful past with Jane; Doug Savant (Melrose Place, Desperate Housewives), as a mock trial advisor whose colleague dies suddenly during a competition; Emily Swallow (The Lucky Ones, Southland), as parole officer of a victim involved in a deadly drag race; and Sharon Lawrence (NYPD Blue) as Dr. Hope Martin, Maura?s biological mother who she has recently connected with.