Plot location! But thats not important yet, lets go finish scanning for a third engineer! The game also has pointed out a destroyed convoy we could scan for more supplies.
...Or finish Alien Biotech first. Resistance Comms is next on the research list, and the AWC is now available to build. I'll put it in top row mid, since I don't see why not place a workshop in the same place i did last time (second row mid), and we already have injuries to speed up the heals of.
Two days later, we got us the new engineer. AWC time cut down to 10 days instead of 20, onwards to the supplies.
Four days later, Comms is researched. Theres a new research I haven't seen before, Rescue Misbehaving MEC...and its instant. Lets see what it is! We'll research Resistance Radio next, since the officer autopsy isn't something we need to get to immediately.
The reward shows as a council mission:

Lets go
steal borrow rescue us a MEC!

Not on screen: Kaladin, Sirus, Rookie Bonnie Price

We on a roof, yo. The MEC is not. Also, Camaraderie bonus.
At 300 to 600 points, a deployed squad gains a buff of +2 Aim, +2 Def, +1 Mobility, +5 Hacking, +5 Psi Offense, and +10 Will

One near-perfect hack (60% chance of success, the bar went all the way to the far end instead) later, our Specialist has gotten himself a nice bonus, along with +3 to Hack. Your new Hack score is 63(+5) according to Perfect Information.
Caroline heads up to the edge of the roof to see if anyone is below us. Strangely, there are no xenos in sight, so the Psiblades hunker down. We're still concealed, I can wait a turn and see if anyone shows up. She moves forward to the furthest end of the roof next turn and only spots two 5 health/3 armor turrets. Going going down and back up through that roof would be
tricky but not impossible to reach the prison cell stealthed, revealed it would be a bad idea. I send one of the Psiblades off the roof into decent cover, and hope they spot something and aren't spotted.

3 Troopers, inside or around the building. At least I know where something is! If there aren't enemies in the prison building, I might be able to sneak in there...

Psiblade Caroline: Now also a ninja.
Psiblade Furtuken: Scouting pretty well.

Good news: Enemies solidly spotted at last!
Bad news: Its two troopers, one advent striker, and a Sectoid Soldier. Soldiers are less psi, more aggression,
have armor, and don't have the sectoid weakness to melee attacks. But well, no time like the present, eh? Rince Storm grenades them.

No enemy kills, but two civilians dead and Rookie Price got a shot in on the Sectoid Soldier. Its still alive though, and she missed her shot at killing one of the troopers!

Thank you, physics! And thank you Jopax for the grenade. Next, Furtukan moves and finishes off the sectoid soldier with soulfire, revealing our first loot of the day. Imiknorris and Kaos manage to smash up all but 1 health on the other turret, Sirus misses the same trooper Price missed with the same ~70% chance to hit, while Storm manages to entirely overkill it with 6 damage.

100% chance to hit on a non-sniper, flanking shot is a glorious thing. So much that it crits, smashing that striker into the ground with extreme prejudice!

Kaladin moves down to grab the loot, another lockbox and elerium core. And then crits for 9!
9 damage with a normal shotgun.

Despite a
stupidly-low (18%) chance of success, Caroline gets the bonus reward anyway. One small intel cache for us, one unlocked door for Cyborg 45, and +3 to Hack for Caroline, for a new total of 18(+5). Our new friend is, sadly, unarmed. But it does have a point of armor and 10 hp, so its not your average flimsy evac target at least. Being a MEC, its immune to fire and poison damage too, and being a Playable Advent MEC, it has a second perk: Jiffy Lube. It will heal at 400% the normal rate when you return from missions due to spare parts, apparently. Sounds pretty nice.

Ack! Advent troopers and soldiers and reinforcements! (advent troopers aren't as special as sectoid ones. They're just troopers with actual armor.) This is a pretty good time to give her aid protocol again, before Urist cleans up the last of the turret's health. Sirus chucks a grenade through the window (this did not blow up the roof as much as I'd hoped), and Kaos clears out the soldier with a pistol shot. We've gotta get on the move anyway. (also apparently he got hurt badly? I did not see the attack that caused this, but its claiming he's on 1hp. Although I did need to reload here, since the game froze on something I'd tried aiming at and then backing out from.) Caroline is now clear to get into cover and smite the other soldier.
Another crit by Athing; this guy also drops loot, which we eventually pick up: advent lockbox, datapad, stock. The remaining trooper dents our MEC friend, and the reinforcements dropped off in a place i can't see. Urist heals Kaos' mystery damage, Furtukan cleans up the trooper we
can see (who drops more loot), and Kaos picks up the loot sice we've got no one for him to shoot this turn. We got another advent lockbox, a laser sight, a PCS: Superior Conditioning, and a sidearm holster.

One roof, and a vanilla officer&co pod is all thats between us and the evac point. Rince Storm grenades two of them: one takes 4 damage and dies, the other falls through the hole in the roof. Caroline soulfires the trooper behind the building (I guess she could see it through the big window), Sirus misses a flank shot on the officer...somehow, and Furtukan disorients the officer. Not the greatest luck with insanity, but it helps.

...
what. You crit the officer from across the rooftops? With a
shotgun?
At 25% chance range? Where the hell did you get that shotgun, Markus Athing?

Not the time, game! And how come I didn't spot them when i blew a hold in that roof...plus theres an Advent demolitionist with them. He's got a better grenade. Kaladin makes a great big mess of the wall but misses the target advent, and Kaos misses his good chance to shoot the sectoid. Sirus gets a critical flank shot (but it was going to hit regardless, pretty much), and Rookie Price throws a grenade the length of the building, only to just barely
not kill the trooper she was aiming for and do 3 damage instead. Athing (who still has both of his grenade launcher grenades) demolishes the sectoid and the soldier's cover, hurts them, and thus is not out of shotgun ammo...yet.
And now for things I forgot to take a pic of: Jopax kills the sectoid! Furtukan kills the demolitionist! Caroline picks up the loot and slashes the advent soldier down at the same time! We get another alien data cache, another lockbox, and another elerium core. Urist hands her aid protocol again because she's out of cover now, but luckily, the remaining advent striker decides to run and overwatch instead.

Kaladin, being the awesome ranger he ended up as, easily dodges the overwatch shot and strikes down the striker! The MEC evacs out, leaving just the team to rush the evac point and leave this place as the wreck it looks like. Price and Storm get out first, followed closely by Caroline, Urist, Jopax, Kaladin, Furtukan, Athing, Kaos, and Sirus the next turn. Phew.
Promotions gotten for Kaladin, Athing, Rince Storm, Adam 'Agamemnon' Jopax, Urist 'Sphinx' Imiknorris, Darkening 'Monarch' Kaos, Min Ju 'Witchy' Caroline, John 'Preacher' Furtukan, and Sirus.
More importantly, Bonnie Price is now a Specialist! I'll get on with purple-ing up your soldier later, Pies. Kaos is gravely wounded (by
what, i have no idea

) for 19 days, hopefully much less once the AWC is built. Our new MEC buddy, Cyborg 45, has 6 days of repairs and is very big in the view soldier screen. Here's the MEC perk tree:
See here for details on the custom perks.

It comes with a 2-clip micro missile launcher, the MEC cannon (which has a clip size of 4), and of course, the MEC armor plating. It also has a utility slot, which I don't know if it works or not so I gave it a grenade. People who want different nicknames need to point out what they want (unless you've already posted it).