When a series of obese corpses are discovered missing body parts, an unorthodox headstrong detective must stop a cult of devil worshipers from further cannibalistic rituals and catch the cult leader.

Cool idea and title.

“Unorthodox” doesn’t feel quite right here as a flaw; first of all, it’s his methods that are unorthodox, right, not the character themselves? Also; it feels very much like someone who DOESN’T play by the rules is going to have an easier time following and catching a band of cannibals than someone who DOES play by the rules? So I would suggest reworking what the actual flaw your character will overcome in act 2 is,

Finally; the obese corpses is a great inciting incident; but you really need the “event” half of the logline to indicate how it directly sets your protagonist on the path to their goal. Either “when he’s assigned the case” or “when he discovers a dismembered, obese corpse while on a routine job …” etc. Bring your protagonist into the first half.