Question

what happened with mr manette for last 18 years​

Answer 1

He is Lucie's father, a brilliant physician, and spent eighteen years "in secret" as a prisoner in the Bastille prior to the French Revolution. He is imprisoned because in the course of his medical practice he learns of abusive actions by two members of the aristocratic Evrémonde family.

Answer 2

$\mapsto$He is Lucie's father, a brilliant physician, and spent eighteen years "in secret" as a prisoner in the Bastille prior to the French Revolution. He is imprisoned because in the course of his medical practice he learns of abusive actions by two members of the aristocratic Evrémonde family.