Plums in alcohol

I take a kind of blue plums just bigger than big, beautiful and ripe olives.

350 g sugar mixture in one liter of alcohol (I take a grappa) and let the sugar melt.

Wash and dry (or leave it dry) prunes (2000 g).

Wash glass pitchers.

I put the prunes after every plum with a needle, in 2 or 3 places (to avoid that the skin is slit).

Add alcohol, how to soak the prunes, the brim of the glass.

I close well and looks at least 3 months, without opening because there is a period of fermentation.