"Space is cold, and many of those who dwell in it are just as cold."
The Northern Expanse is no different and represents a microcosm of the galaxy at large. The Romulans, the Breen, the Ferengi, the Cardassians, and anyone in between all threaten peace and free passage and trade in the area of space to the galactic north in Federation space.
The year is 2392 and it has been several years since the Hobus incident, which did a lot of damage to the Romulan Star Empire, although did not wipe them out entirely. The Kingons and Breen and Ferengi and others would have enjoyed that all too much. But as the years roll on and the Federation try to assist the Romulans, others continue to try to take advantage of that.
Years before Hobus, resistant groups set out to oppose what the empire was becoming. Pirate attacks increasingly became a problem in the Northern Expanse and thus Task Force 56 was formed to try to figure out what was going on and bring peace and stability to that area of the galaxy. The Rihansu Resistance that was started so long ago, the Romulan Empire, the Breen Confederacy, or individual pirate groups from all types of species' dissidents - who was behind all these attacks was largely unknown, but they increased in Federation space when TF56 arrived and began seeking out the Resistance as well as these pirate bases and colonies.
The Federation and Starfleet want to assist the Rihansu Resistance to figure out what is going on. They want to continue to support the Romulan Empire. They want to continue to stave off the brazen behavior of the Breen. They want to put an end to this mercenary threat. They want their cake and to eat it too.
The challenge of Task Force 56 in the Northern Expanse is to balance all these wants and yet prevent their own task force from being ripped apart by the very things they wish to contain and help. The Tal'Shiar would undermine any relationship with the Romulans. The Gorn, Cardassians, and Klingons might just take advantage of any gap or weakness, even way up in that area of space. And the relentless toil in the midst of all of this will challenge any ship and officer operating therein.
"Space is cold", but there are those who bring a warm torch to the Northern Expanse, putting light and warmth on those who will accept it. Task Force 56 brings that torch.