While this map is not immensely difficult, there are a few key things that are worthy to note. First and foremost, this is an indoor chapter, so all of your mounted units are unfortunately going to have to dismount. The Mov Plus is located in the topmost chest and provides move +3 to whoever it is used on, so it's a fantastic item to obtain. Getting it, however, is somewhat difficult. You'll need to rush your strongest units forwards as quickly as you can manage, otherwise the Thief that beelines his way there will grab it and run off. This is complicated, of course, by the units hiding in the centre, the mages, the thief sword myrmidons, and the mass of Shadow Lancers on their way (showing up in groups of 4 for 4 turns). Note that one of the lancers has slightly different stats - that's actually Arkis in disguise, so do not kill him by accident.
If you picked up the mug skill book in the previous chapter, then you can use it to grab any items stolen by all the myrmidons wielding thief swords. If not, then these are best dispatched at distance with spells or bows. The biggest roadblock for your weaker units is the central area which is locked and prevents you seeing what's inside. Inside the central area are two Arbalest archers (2-4 range, accurate) a Physic bishop, a high mage with Tornado, and another archer with a Chu-Ko-Nu.
Additionally, the prison cell occupied by allied clerics is actually 7 Shamshir bandits who are disguised as clerics, and upon opening the door a short cutscene will play revealing them as such. As long as you have a tough unit like a trained Billford, Bartz, or Narron etc who can plug the doorway, you can usually kill all of them on enemy phase as they are not very powerful, and gain 7 money bags in the process.
Killing Rentzen is very hard, and fighting him with Vega's Rukuud makes it very easy (if you've been training him), but be careful, as he still has 80% crit rate. Killing him with Vega or Julia. The real challenge is Golgoda, a Swordmaster wielding a Brave Sword and having several powerful skills, including Astra. He's a lot more powerful and should be dealt with carefully.