Bernadette and Mrs. Wolowitz have a "get-to-know-ya" lunch at a deli. Howard hopes that once his mom sees how wonderful Bernadette is, she'll welcome her into the family like a daughter and he'll be able to finally tell her about the engagement. When his mother returns and heads into the bathroom, Howard takes the opportunity to tell her they're getting married. The news is met with silence.
We later learn that Howard was eventually able to knock down the bathroom door, pick up his unconscious mother and drive her to the emergency room. The gang all go to check on Howard and his mom at the hospital. Howard is convinced that the news of his impending marriage caused his mother to have a heart attack, or a "heart-attack-like-event" as the doctor put it. Bernadette is now convinced that Howard's mother hates her.
At the hospital, Sheldon is paranoid he will contract an infectious disease and while trying to avoid it, he accidentally walks into an isolation room and is thus exposed to an infectious disease.
Penny and Priya go off in search of good coffee and end up bonding with each other through stories of Leonard's prowess in bed. In the end, it turns out that Mrs. Wolowitz was just suffering from food poisoning and Bernadette was the first person she wanted to see to make sure she was okay. Bernadette gets mad at Howard for making her believe she caused his mother's heart attack.