This is the first mission in Episode Two of the game proper.
The marker for this is right by the Tranquility Temple teleport point. The finalish boss has both both extensive shield and armor capabilities, so pick your team accordingly. If you have to chose between one or the other, a shieldbreaker will be more useful than an armor breaker (because armor doesn't regenerate).
Your first objective is to check out a reactor exhibit at Milae Technologies.
Follow your markers up to a console. There'll be some light explosive booms along the way, but no armed resistance. Hack the console for some exposition.
The next console, a few floors up, will have the same ratio of dramatic explosions to enemy actions. It's only afterwards you'll encounter your first wave of baddies- mostly helltroopers led by a helltrooper commander
Jumping over to the south building will give you a vantage on the whole lot, otherwise lurking on the level just beneath them will let you more easily pick them off one-by-one. When they're all sufficiently dead (which is to say- dead), hack one last console on the upper level.
This clues you into some major uncoolness going down on the planetarium, but before you investigate, you may want to snag the crystal floating over the roof here.
Note that, despite the beacon, your checkpoint is not the planetarium itself, but your vechicle. Drop down to street level to retrieve it.
Drive over, and clear the area of the low-level troops infesting it.
When they're down, hack the indicated console to cue a cutscene and the villain fight.
In this first phase, Hammersmith is heavily shielded (Fortune's dual pistols are an ideal way to strip these shields away). Dodge or take cover (non-destructable cover, ideally) when Hammersmith fires. Once his shield has been popped, hack the designated console.
This launches phase two, pitting you against a heavily armored Hammersmith and his goons.
Take out the goons first, then pick apart Hammersmith at your leisure, ducking behind a pillar when he fires back. It's not a bad idea to hang close to one of the non-destructable bits of cover here, so you've got a place to reload while he counterattacks.
Take out Hammersmith one last time to send him into retreat. Hack the indicated console for some fireworks.
This completes the mission, granting XP, cash, and gadgets to all party members involved.