Hide and Seek (STO)
From Trekipedia
Stardate Unknown: Coded messages sent by an Undine infiltrator lead you to a distant nebula where enemies lie in wait.
Captain, this mission briefing is classified.
Starfleet Intelligence has been working on cracking the coded message sent by the Undine agent you exposed at P'Jem, and we think we have something.
There are several references to the Paulson Nebula in the data. That is an area of space near the Lackey system that we don't know much about. Starfleet needs you to survey the nebula and find out why the Undine have an interest in it.
Be careful. When the Enterprise-D was in the area, it reported that the composition of the clouds may screen opponents from your sensors.