You've found a strange Almain who has been hiding in the sewers of Idylla.
The Main quest 'Shapen in Iniquity' requires you to enter the Sewers and find the 'Arkes' Circlet'. Once you’ve found it, you can leave the sewer and find the strange Almain later on, or you can choose to do it right away. Before you can do so however, you’ll need a Detect Hidden skill of at least level 5 or higher, because there’s a hidden door that blocks your path.
Where you found the 'Arkes' Circlet', instead of going back, continue onwards. Keep going until you can choose to go right or left. Go left, where the hidden door is. Open it and continue to follow the path. Once you jump on the big platform, you’ll see a giant square hole right in front of you. Jump down there and you’ll see the Almain right in front of you. Speak to him.
You can also check the local world map for a small white arrow that says 'strange man'.