Gambler's Ruin is the squad story focused on Jester, Teresa, and Connor. The combat mission in this is called The Roguish Patient. This is available at the earliest in Chapter 2: The Liberation of Reine after Connor is recruited.
This map takes place on the same one as in Interlude 2: The Other Kai. Some minor differences include indestructible walls and barricades along certain areas of the map, preventing access to them. Most of the area to the west of the river is inaccessible. There are also grenadier shelters along the west bank of the river, mostly in the lower elevation section.
Jester, Teresa, and Connor will start by the Federation base camp in the SW corner of the area south of the river and seek to eliminate all Imperial forces scattered throughout the map.
Now then, I believe Jester went running off in this direction...[]
"He ran so hard he went off base. Squad D should be patrolling the area, but they haven't seen him anywhere. Hehe. I can tell this is going to make for exquisite writing material!"
Location: Training Field
Description: Prevent the Imperial advance by defeating all enemies. The story of Connor, Teresa, and Jester will end if any of them die or an enemy reaches their objective first.
"Now, let's be off! Here starts the greatest story yet to be told!"