A gorilla is exposed to a chemical from a secret genetic experiment, which causes the gorilla, a wolf and a crocodile to grow to enormous size and wreak havoc.
Laura is horrified to learn that her role in a school play demands that she and Steve share a kiss onstage; Carl is forced to do menial tasks for his boss.
After Steve begins sleepwalking into Carl's bedroom and assaulting him with a newspaper, he has his young neighbor hypnotized in order to uncover the reason.
Chandler refuses to give back a cheesecake accidentally delivered to his apartment; Phoebe gets angry with Joey when he blows off dinner with her for a date.
Monica regrets telling a woman about a discount bridal shop when they fight over the same dress; Joey and Ross discover that they're dating the same girl.
Penny and Leonard plan for a paintball game that devolves into chaos when Sheldon becomes jealous of Amy; Raj spots Anu spending time with her ex-boyfriend.
Sheldon is elated to help Bernadette and Howard tackle bureaucratic paperwork; Leonard is unhappy when he is excluded from a scientific project by his friends.
Wil Wheaton organizes a celebrity Dungeons and Dragons that the gang is determined to get the last open seat to play in through betrayal and deception.
Howard babysits the children while Penny and Bernadette attend a pharmaceutical sales convention; the rest spend the day performing experiments on the children.
Raj publishes a paper that suggests he has stumbled upon alien life; Leonard aspires to become the principal investigator during a study in plasma physics.
Kripke stumbles upon evidence that suggests Dr. Pemberton had plagiarized his college thesis; Howard learns multiple waitresses used to have a crush on him.
Bernadette and Howard prepare to spend time away from their children for the first time; Penny and Leonard attempt to keep a secret from being exposed.
Phil invites his old high school girlfriend over; Jay accidentally kills Manny's pet turtle and tries to cover his tracks; Mitchell stands up to his boss.
Stan loses his confidence after a car salesman gets the best of him; Roger and Steve try to get to first base with the popular girls at a makeshift drive-in.