After 12 years of marriage, his wife Judith, kicks Alan out. He turns to his older brother Charlie for help. Charlie has trouble adjusting his carefree lifestyle with the presence of his 10 year old nephew.
Alan punishes Jake for an incident at Judith's house. Charlie is lax in enforcing Alan's restrictions, then some seagulls invade Charlie's house as a result of Jake's actions, Charlie has to learn how to discipline his nephew.
As Charlie tries to write a new jingle, Berta quits. Alan tries to convince her to come back. Leaving Charlie to get Jake ready for a dinner. And Rose tries to get Charlie's help to prepare for a date.
Jake sees a butterfly tattoo on the firm bottom of a surfer-chick friend of Charlie's, which is the start a string of harmless events that become larger and more disastrous with each action. This is not unlike the famous chaos theory's Butterfly Effect, asking if the flap of a butterfly's wing in Brazil, could set off a tornado in Texas.
After being tricked into helping Alan and Judith produce Jake's classroom musical, Charlie is flattered to find out that the kids know all the words to his jingles. Alan is blind-sided with divorce papers from Judith, causing strife which results in Charlie, who refuses to deal with the pre-pubers without a snootful, having to produce the play on his own. Jake is crushed when he realizes that a reconciliation between his parents may never happen.
Thanksgiving winds up being the least thankful day of the year for Charlie, who has to bribe various members of his household to even come to a traditional turkey dinner. Not only are the usual feuds in evidence (leading to a turkey-carving right out of "Psycho") but Judith's parents are actually sympathetic to Alan and hostile to their own daughter for her "fling" with lesbianism.