In a small saucepan combine the water and sugar. Bring to a boil, stirring occasionally, and remove from heat. Cool.

To make the cocktails combine 1/4 cup of the cooled simple syrup, plums, thyme, and lemon juice in a bowl. Muddle until the combination turns purple from the plums.

Place ice in 4 tall glasses.

Pour 3 tablespoons of the simple syrup and plum mixture in each glass. Fill to the top with champagne.

Garnish with fresh plum slices and thyme sprigs.