"I don't think being too clever about this is going to help. If we try and pick off his associates ahead of the raid, failure means we alert Lamm to what's going on, with...unpredictable...consequences. No, since they all sleep in there with him, I think we're better off hitting them all at once with all the forces at our disposal - which happens to be just the six of us."

"I agree with Deklen that a night raid will be difficult to pull off as well. We'll need light and we'll need to break down at least one door, which increases the odds of us being discovered and the time Lamm has to react."

"Right now, I believe the easiest way for us to get inside is to split our team and go in during daylight. Most of us walk straight in through the sliding bay doors during the day, when business is in full swing. We identify ourselves as contractors for the Bank so it won't seem suspicious that we're coming in fully armed, and start raising an almighty fuss about Lamm and his crew being squatters. Either they try and throw us out, in which case the fight is on, or we get them worried enough that they try and make a deal with us."

"While the first team is providing a distraction, a second team busts its way in through the door on the boardwalk and takes them from behind. If we hit fast enough and hard enough, it's not unlikely that we can break Lamm's morale and force a surrender."

"But whatever we do, the most important thing to remember is that we want to take these fellows alive and we want to keep damage to the fishery itself to a minimum. Naturally, we also want the children safe and sound," Lucian says with a nod to Isara and Marcus.

"I'd suggest that everyone makes sure they have a club or sap on hand for the raid, and that we only draw steel if things get really hairy. We also need to make sure that all of these villains know that surrender is an option - in my experience, even desperate criminals would rather live another day than die on the spot. We could also shop around among the city's alchemists to see if they have any useful substances that can help knock out the opposition."

Spoiler: Fairly cheap stuff I think might be useful to suppress opposition quickly
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Several of these are from sources besides those that were okayed during character generation, so they would require GM permission.
Nets (PHB, p. 119) - Ranged touch attack to entangle foe and allows opposed Strength check to control movement. Exotic weapon though.
Drow poison (DMG, p. 297) - Injury poison, causes unconsciousness as initial and secondary damage. DC 13 to resist.
Flash pellets (CA, p. 119) - Blind everyone within 5 feet for 1 round and dazzle them for another. DC 15 Fort save to avoid the effects.
Screaming flask (CM, p. 135) - 15-foot cone, does 1d8 sonic damage and deafens everyone in area of effect. DC 15 Fort save negates effects.
Roach paste (DotU, p. 94) - injury poison that causes nausea for 1 round, then filth fever. DC 12 to resist.
Red tidewater (Planar Handbook, p. 77) - splash weapon that causes blindness. DC to resist varies with direct hit or splash. Also causes blinding sickness.
Slumber sand (Sandstorm, p. 103) - target struck falls asleep for 1 minute. DC 15 Fort save to resist.
Stinkpot (Stormwrack, p. 108) - smoke fills 10-foot cube. Living creatures must make DC 15 Fort save or become sickened.