Speak to Vernon Tinworthy ( 807, -14, 42 ) /waypoint 807, -14, 42, on the top of the stairs (third floor) of Fish's Alehouse. He doesn't trust you, and sends you out to speak to several other people and to gain their trust.
Speak to Mary Dillon ( 801, -23, 60 ) downstairs. Avoid asking about the shield, and instead console her about Thierry.
Head to South Qeynos and speak to Thierry Dillon wandering the streets. Choose the following in conversation:
"Sounds like you're a compassionate person. And a smart one!"
"She's not a very friendly sort."
"Ellinnea couldn't help boastings; a trasnparent effort to put you down, really."
"Your device would be much better, I'm sure."
"You're a genius, Flizgibbert!"
Head to The Baubbleshire and speak to Arbuthnot Jumroller ( 865, -12, -419) on the hill overlooking the waterfall. Praise Towser and ask about the truth potion.
"You're friends with Towser Flizbiggert, aren't you?"
"I hear Towser's a great teacher"
"I met him through the design contest"
"Truth Potion?"
Head to North Qeynos and speak to Jo Ironshield ( 284, 17, -167 ) on a hill just north of the bank. Grill him and get the truth potion.