Saugus Ironworks is a small location inhabited by enemy gang that favors fire. Due to that, you will mostly meet here enemies with Molotov's cocktails and flamethrowers. Sometimes, the gang is fighting with neighboring shooters that occupy part of the base on the highway.
The location is related to the Out of the Fire quest which you will receive on the Finch Farm.
There is a miniboss in the location - Slag. He is also related to the quest in this location.
You can find a unique weapon, "Shishkebab" melee weapon, after killing Slag.
In Slag's room there is an Explosives bobblehead and Picket Fences magazine to be collected.