Check your CCTV monitors and listen to the prepper at the safe house. He will give you the next MAIN quest.
Head to victoria memorial, green park specifically if you have it on your map. You should have touched a tip of this area earlier if you were searching.
Follow marker head to the tent, We need the key card in there. Don't worry about the water for now, just head and loot the tent.
Follow marker and use the key card on the door, you should find a dee letter, as well as some C4. Then a Cutscene with the Ravens of dee and sandra.
The water !
Making your way through the water is scary but keep your cool. Just go through it nice and fast. Use the middle island, to take out some zombies if you must.
Your heading to the right "island" or patch of dry land. To the left is the junction CCTV box. Anyway stick Right for the Main quest.
You Eventually come to an area where you can place some C4. Use it and this will open up a pathway. Follow it until you reach the Pier.
The Pier Sniper
Pick up the snipier rifle. Start picking off the zombies. There will some strange objects that distrupt your prepper pad. Destroy these computers or whatever they are.
Make your way towards the marker. Enter the most difficult part of the game, the catacombs.
Things To worry about...
1. Falling and Dying
2. Exploding Zombies
4. Being very scared and messing up and well.. Dying.
5. So just DONT DIE.
Honestly this is much much easier said then done. The biggest concern is to be on the look out for exploding Zombies. Don't forget that EXPLODING ZOMBIES. Look them up in this guide.
Make your way to the marker. Scan the marker and you will now upgrade your pad to decipher the angel language.
Now note, you can decipher all those werid white chalk like drawings you might have seen earlier. Though it is easier said then done.
So there should be another marker after getting the decipher. also don't forget to scan the QUEST MARKER to actually continue the quest, then the message to unlock the key coded door.
Yeah its awesome, moving on.
The key code door leads to the city streets. All hell will be breaking loose. Tons of zombies, tons of carnage. Personally I died here and ended back up at the safe house. Which will bring up the next quest either way.
If you do live, like i did on my 2nd playthrough, it still results in the same ending. The helicopter will crash. It just depends where you will end up the safe house, or near the man hole.