Sixteen years have passed since Lord Voldemort killed the Potters and took over the British Ministry of Magic. Mudbloods are continuously captured, some are killed, others are enslaved. Voldemort reigns with fear and no one dares to oppose him, that would mean instant death.
So why is it that now there's this mysterious group of people thwarting his attacks on muggles? It's because he couldn't eliminate Albus Dumbledore. Voldemort thought that killing Harry Potter, the one prophesied to destroy him, would make him invincible, but he was wrong, so wrong.
Because Dumbledore has been preparing the new Order of the Phoenix in the shadows with the help of the Marauders, minus Peter of course. They've been waiting for their time to come, for Harry to grow and for their perfect weapon to mature. He's confident in his plan, in his target. The Malfoy boy was in the best position for them to take advantage of, he wouldn't see them coming.