On the last year of Hogwarts, the seventh year, Mattheo Riddle and Tom Riddle, sons of Voldemort and Bellatrix Lestrange (née Black), of 17 and 19 respectively, are charged with a mission from their father to get pure bloods that aren’t in the death eaters to join, even if Tom did finish Hogwarts already and Mattheo is in his last year.