New roommate Deena moves into the house and is confronted with hostile reactions from some of the roommates. The house gets off to an interesting start when Snooki confronts Vinny about him and her best friend Ryder and Deena "accidentally" gets naked in front of Mike. Leftover tension from Miami spills over to Seaside Heights when unresolved issues among the girls explode on the first night.

The fight between Sammi and JWoww causes additional tension in the house. Ronnie and Sammi continue to isolate themselves, missing the first family dinner, to the surprise and disappointment of all the roommates. Mike lets Ronnie know about the general feeling at the house. Ronnie decides to hang out and have fun with the rest of the house, leaving Sammi feeling all alone and reminiscent of Miami.

Sammi sets out to make amends with Snooki and Deena. A night in the club turns romantic for Jenni when she runs into a old flame named Roger, who may or may not have a girlfriend. Deena gets kicked out within the first five minutes for being too drunk. Mike meets one of the girls he hooked up with last year named Paula and Pauly's stalker returns and throws a drink at him. The next day Snooki is extremely hung over and has to go to work. After sneaking a couple of drinks she runs off drinking more and more. After a huge crowd appears to watch her creating a scene Snooki is arrested.

Snooki is released from jail but faces her father's voice on the phone which isn't happy. Jenni continues to meet with Roger and quickly grows feelings for him. Tom continues to call the house and cause problems with Jenni escalating into a heated arguement on the phone and a destroyed relationship. Snooki is lifted from her depressed state after she meets Nick who she hooks up with. Deena meets a Ronnie look-alike only to find out that he has a girlfriend. Later, Jenni has to return to her home because Tom left leaving her dogs to die. She and Snooki leave the Shore and reach home within 9 hours to find her dogs fortunately safe but her most important items including a hardrive stolen.

Snooki's friend Ryder stops by for a visit and lucky enough its her birthday. Snooki and Jenni return to Jersey with Jenni's dogs who are welcomed at the house by everyone. Sammi and Ronnie's relationship continues to strain and after a heated argument after the club, Ronnie throws all her stuff around the room and tells her to leave. Ronnie starts to second guess himself. Jenni comforts him and they bury the hatchet from Miami. Mike brings home a girl, but her friend is wandering down the house so Vinny pulls out the Grenade Whistle to warn Mike. Vinnys girl's family comes to pick her up which make Vinny uncomfortable. Jenni gives Ronnie a hug which is caught by Sammi. Sammi loses it and thinks she is all alone in the shore house. As a response to the newfound friendship between Ronnie and Jenni, she punches Ronnie in the face. She quickly plans to leave but with the help of everyone she apoligizes to Ronnie and stays. Jenni and Roger continue to date and also Deena and Dean, but Mike finds out a dirty secret which ends their relationship. Also Snooki and Vinny buy a stripper pole for the house and Sammi and Jenni make up and become friends again.

Snooki meets a guy, but he may or may not be engaged. Pauly D. makes peace with an old enemy; and Ronnie's hard partying takes a toll on his relationship.

Ronnie and Sam end their tumultuous relationship with a nasty breakup that prompts Ronnie to destroy all of Sam's belongings. Later, she considers leaving the shore for good.

After Sammi leaves the house, Ronnie is an emotional wreck. With the girls taking Sammi's side and the guys not knowing how to cheer him up, Ronnie feels like he has no friends left in the house. Meanwhile, The Situation tries to hook up with Pauly D's ex-girlfriend.

Snooki's hook-ups haunt her; Mike pranks Deena and Snooki; the guys ditch Mike.

Sammi returns to the house; Snooki's feelings for Vinny deepen; Mike believes a hook-up smells like cheese.

Vinny and Pauly D take a road trip to Staten Island. Roger becomes more than just a rebound for JWOWW. The Situation reveals Sammi's shady ways, causing Ronnie to question his love for her.

The roommates say goodbye to another summer at the Jersey Shore. While one couple reaches a crossroads in their relationship, another couple makes it official.