SPOILERS: Last 4 episodes of Rizzoli & Isles Season 4

• Paddy Doyle asks Maura to let her biological grandfather, Patrick Doyle Sr., temporarily stay at her house.
• Casey is made a colonel and gives Jane an ultimatum - He will re-enlist unless Jane married him. It's believed that's how the season ends.
• Jane and Maura get massages in episode 5x13.
• Tommy Rizzoli and Frank Rizzoli Sr. will appear in 5x14. Tommy is also in episodes 15 & 16.
• Hope tries to make amends with Maura.
• Tommy announces some big plans - an engagement.
• Frankie sustains an injury and ends up getting closer to Maura.
• Lee Thompson Young's stand-in and body double is featured in the final episode. (via Nanci Cascio)
• Tommy starts slipping back into old bad habits and fights with Frankie.
• Jane reveals some shocking news. (Possibly engagement to Casey.)
   

Source: All around the internet.