Your question is Resolving a Complex Production Bug. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Tell me about a complex production bug you had to resolve. How did you identify the root cause, what actions did you take to restore service, and what did you put in place to prevent the issue from happening again?