Remove giblets from game hens, if present. Rinse hens. For brine, in a stainless-steel or enamel stock pot or plastic container combine cranberry juice, syrup, and salt; stir to dissolve salt.
Carefully add game hens to brine. Cover and marinate in the refrigerator for 4 hours, turning hens occasionally.
Remove game hens from brine; discard brine. Rinse hens and pat dry with paper towels. Tie drumsticks to tail with 100%-cotton kitchen string.Twist wing tips under back.
For a charcoal grill, arrange medium-hot coals around a drip pan. Test for medium heat above pan. Place game hens, breast sides up, on grill rack over drip pan. Cover and grill for 50 to 60 minutes or until hens are no longer pink (180 degrees F in thigh muscle). (For a gas grill, preheat grill. Reduce heat to medium. Adjust for indirect cooking. Grill as above.)
Remove game hens from grill. Cover with foil and let stand for 10 minutes before carving. Makes 2 servings.