In a medium saucepan, combine the cranberries, sugar, and water.
Bring the mixture to a boil over medium-high heat, then reduce the heat to medium-low to maintain a gentle simmer.
Cook for about 10 minutes, stirring occasionally, until the cranberries have popped and the sauce has thickened slightly; the berries will be soft and the liquid will be syrupy.
Carefully pour the hot cranberry sauce into a heatproof bowl or mold; a 2-cup capacity works well.
Press plastic wrap directly onto the surface of the sauce to prevent a skin from forming.
Refrigerate the sauce for at least 4 hours, or until it is completely set and jiggles like firm Jell-O when the bowl is nudged.