<step one>
Talk with AIKO about freeing Synthea from his brainwashing after having reintroduced the AI to SISSI's systems.
For more information about AIKO's infiltration, click here.
<step two>
While completing a coffee order at Cafe 52, Candy will pull you behind the counter to talk to you about mixing an antidote to cure Dr. Synthea if you have completed her de-bimboficiation plotline.
For more information about Candy's personal plotline, click here.
<step two alternative>
If you have not completed Candy's plotline, Mrs. Antlers will give you the details about what has happened to Dr. Synthea after you free her from her own brainwashing.
<step three>
Ask AIKO for the formula mixing the antidote.
<step three alternate>
You can raid Dr. Twig's laboratory looking for information during a nursing assistant shift. You will find information about Dr. Twig's sister. Call her and she will give you the details you need.
<step four>
Tell Candy that Dr. Twig has made a new candy after work. Follow her into the lab and mix the antidote while she distracts Dr. Twig.
<step four alternate>
You can mix the antidote in Dr. Twig's lab after finishing a shift as his nursing assistant.
<step five>
AIKO will meet you in the elevator and direct you to go to Dr. Synthea's office.
<step six>
Go to the office and administer the cure to Dr. Synthea. This will finish the questline.