Oracle's voice speaking to you through the comms during your patrol was the only thing alerting you that Nightwing needed help. Apparently, he'd been ambushed by a little too few goons and just barely made it away. Chinatown, Bleake Island. Somewhere near there according to Oracle. Nightwing's tracker had been busted while he fought off the goons and the most that could be taken from it was an approximate location.

Damian had insisted on going to find Dick, claiming he could find him faster than you could, but Bruce shot him down, knowing Damian and Cass' patrol was on Miagani island, far from Chinatown.

You found Nightwing slumped in an empty fire escape of a darkly lit alley in the outskirts of Chinatown. Blood stained his lower lip and parts of his suit and a dark bruise already blossoming around his right eye as well as everywhere else on his body. His eyes were glazed over. He'd likely taken a couple of very hard hits to his head. Sometime early on in the fight. That would explain his struggle to beat the goons.