Conversation so far:
What can you tell me about The Vicomte of Bragelonne: Ten Years Later?
After 35 years of loyal service, D'Artagnan resigns as lieutenant of the Musketeers.
Why would that make D'Artagnan resign as lieutenant of the Musketeers?
D'Artagnan perceives the young king Louis XIV as weak-willed.
What happened next after d'Artagnan resigns as lieutenant of the Musketeers?
D'Artagnan resolves to aid the exiled Charles II.
How does d'Artagnan help Charles?
With d'Artagnan and Athos' assistance Charles II is restored to the throne.
What happened next after Charles II is restore to the throne?
D'Artagnan is rewarded richly.
What did Charles II do once he was in power?
D'Artagnan is rewarded richly.
Are there any other interesting aspects about the The Vicomte of Bragelonne: Ten Years Later article?
Jean-Baptiste Colbert tries to bring about his superior Nicolas Fouquet's fall by bringing to King Louis XIV's attention that Fouquet is fortifying his fief of Belle Île secretly.
What did King Louis XIV do after being brought to the attention that Nicolas Fouquet is fortifying his fief of Belle Île secretly?
King Louis XIV persuades d'Artagnan to re-enter his service to investigate Belle Île, promising him a substantial salary and promotion to Captain of the King's Musketeers on his return.

Question: What did he find during his investigation?
Self-contained rewrite: What did d'Artagnan find during his investigation of Nicolas Fouquet?