A somewhat confused tale of three lots of siblings, an extra-marital affair and an inconvenient death sees Kirstey Alley as Marjorie Turner, the doctor's wife who has one brief fling with Sam Elliott before he croaks, thanks largely to their furious squelching.
Panicked, she returns home. Meanwhile the body is discovered by a salesman (Pullman), who can't report it because his brother (O'Neill) is running for Police Chief and he wouldn't stand a chance with a murder suspect as a brother.
Flitting in and out are Marjorie's wacky, devil-may-care sister (Gertz) and the rest of hubby Harry's smug medical family (notably his sister, Fisher), while Gertz falls for O'Neill and it becomes apparent that Harry's long-lost brother has gone missing.
Still with us? If it all sounds confused, that's t because it is. And therein lies the essential problem with Carl Reiner's latest work. Although Alley shows herself to be a comic actress of genuine talent, and while the observations on sibling rivalry and familial relationships are often razor sharp, there are just too many characters and too much going on for Sibling Rivalry to really fire on all cylinders.