Well. First of all. Make sure you challenge the gym there. After that, go and follow Drayden to his house. After a chain of events, You will need to traverse the icy opeculoid city and Defeat all the Grunts there.
After you've done that, Make your way to the gym and you will have another battle. You will then have to find the member of the Shadow Triad who is in the very South East of the city. Afterwards, head to Undella town and take the Marine tube and go from there.