From Lisa Frame cap Library
According to Wikipedia - Solo and Kuryakin devise a scheme to break into a vault under a casino where THRUSH keep their funds. To catch a thief, you need a thief and that's where Marcel comes in. After being threatened with blackmail by Illya, Marcel reluctantly agrees to help them, but he wiggles and squirms like the weasel he is. Still, he doesn't count on Napoleon and Illya and their single minded purposefulness.
So, do you think Marcel was without an redeemable qualifications or were Napoleon and Illya right to put their trust (or lack thereof) in him?