Some very basic stuff about good old Cordy:
*Though she is in a rather low class job, she has recieved an extensive education similar to most of the upper classes(ie she can quote Austen, Webster and so on with ease).
*Though she is aware of most of what it takes to be a detective, and displays some proffessional aspects ultimately she is inexperienced and little more than an amatuer(she failed to protect Clarissa, she gains a large part of her income from rescuing felines, also Clarissa's husband basically tells her she shouldn't feel responsible because she is an amatuer).
You should be able to build on from this.