Am I missing something, or did Drake at best only partially complete this one?
He lets Dave escape when Lena interrupts his apprehension. This leaves Dave unpunished for the murder of Ellis -- and free to kill again.
Soon after, Drake prevails over the head of the murder for hire organization and his henchman. But he fails to learn who hired them and why. So again, the true killer -- identity unknown -- goes unpunished, and free to continue their deadly ways.
Otherwise, great episode. But has there been another where Drake's failed so spectacularly?