A main character with a split personality is not a new concept, most readers will understand the premise so best use that fact. It sounds like the hook, in this case, is the split personality why not put it front and center – you’re not giving away the ending just being clear on the premise. Ultimately the goal is to find the kidnapped fiance, Joe will help find him and along the way discover that Angelica is the kidnapper. We, the audience, will either discover Angelica’s true identity with Joe or at the end (like in Fight Club). I tend to think that the ‘surprise’ ending would be cliche, now day and age, and the story would be better off exploring the reality of living with split personalities instead of using them as a supposed ‘twist’ – most audiences will get it long before it’s revealed.

Aside from that the structure of the logline needs to emulate the story, i.e start with an inciting incident, describe a main character and then his or her goal. Right now the reader is left to assume that Gunner is the missing fiance, and wonder what Joe’s motivation for involvement really is.