Hidden Tax (Side Quest)
In the small village on the southern edge of Lake Mareotis (very near where you enter the region), Bayek will come across a woman looking for someone to rescue her husband.
There's an unattended boat at the end of the dock here. No one minds if you borrow it.
Get close and scan to see that the wayward husband is completely surrounded by crocs. You'll need to kill them before you can enact a rescue.
Speak to Klaudios and he'll automatically start following you. Take a boat back to the mainland.
Once there, revelations ensue.
Beat up the two toughs. They're not very dangerous, and Klaudios is actually a pretty fair fighter- so do watch out for friendly fire. When the coast is clear you'll gain Klaudios' gratitude, his wife's anguish, and mission completion.