While trying to stay out of Alice’s business, Jimmy has to “Jimmy” an insecure Brian. Gaby leans on Paul for advice after her sister drops a bomb.

Howard and Bernadette welcome their new baby and Sheldon and Amy celebrate Amy’s birthday.

Sheldon becomes agitated when his regular barber is out sick. Astronaut training causes Howard to reconsider wanting to go into space. Penny beats Leonard in chess, the first time she…

Penny tags along on Sheldon’s first ever date; Wolowitz finds a new use for a robotic arm.

Penny wants to throw a surprise party for Leonard, but Sheldon’s indulgence at an electronics store throws her off-track.

Brilliant physicist roommates Leonard and Sheldon meet their new neighbor Penny, who begins showing them that as much as they know about science, they know little about actual living.

Conrad goes head-to-head with Lane when he disagrees with her over a treatment plan for a terminal cancer patient. Tensions rise when Jude inserts himself in the middle by offering…