An amnesic secret service agent of Arab origin must recover his memory to clear his name and stop his terrorist brother from detonating a dirty bomb on US soil.

Both, the first one years ago forced him to make a choice.
The second one put him back to the same situation.

Which attack is the inciting incident?

Star Trek:Voyager has an episode on the very same subject you described. It is the episode 4.22 called "Unforgettable". If your memory were erased and you were put in the very same circumstances, would you fall in love again with the same person? It is a very moving bitter sweet love story.

Not really a logline, but a mini synopsis of my project.
After the death of their third brother in a drone attack, one brother joined the French service service, the other one a terrorist cell. When a failed attack that kills their remaining baby brother bring them together, both have to face the consequences of the choices that they made years ago. Will they betray each other or their cause?

My story is more about: are we shaped by the events that happen to us or are we shaping the events that happen to us? Do the events dictate our choices or do our choices dictate our future events?
Two brothers, two different destiny. Both shaped by the same failed drone attack, but both responded diametrically opposite way.

>>>The amnesia is just a mechanism to put him in a situation where he has to make a choice based not what he knows, but on what he believe to be right or wrong. It forces him to remake the same decision he made years earlier. But there is no guarantee that he will make the same choice again.

Now you're probing into something intriguing:

1]A set of circumstances force you to make a pivotal, life changing decision.
2} Subsequently you lose your memories in an accident and have to rebuild your whole identity, your whole life.
3) Events conspire -- for that's what a plot is, a conspiracy against the protagonist-- to recreate the same circumstances.
4] With a reconstructed personality and a new set of memories,would you make the same decision again?

THAT is an interesting premise. Dare I say, a hook. But it seems to me, it is not readily apparent in your current logline. Best of luck refining your concept and developing your story. If you can deliver on the premise above, I'll eagerly buy a ticket to the see how you play it out.

Regards.

I disagree with you on this point.
To me to relate to a protagonist, I need to know his motivations and sometime his background history. IMHO, if you don't know what will be his ultimate goal/decision and you don't him, you just watch events unfolding from a detached perspective.
With the amnesia, you follow the same moral, and intellectual journey that he does. It also allow me to use flashbacks. The presence of the terrorist brother is a way to entice him to the dark side. We all have dark side, revenge is a powerful motivator. The amnesia is just a mechanism to put my hero in a situation where he has to make a choice based not what he knows, but on what he believe to be right or wrong. It forces him to remake the same decision he made years earlier: to go on the right side and become a secret service agent. But there is no guarantee that he will make the same choice again.
I want the movie to have suspense, but to me suspense arises when the spectator knows something that the hero doesn't: a bomb is ticking, ...; or a bad situation is unfolding and there is no easy solution out. But you have to care for the hero.
If the spectator doesn't know and genuinely can't expect to know whether the protagonist will do the right or wrong thing, then he or she can't root for him. Without that extra emotional involvement, there is no suspense.
You may still have surprise or twist. Surprise or twist is when an expected action/event occurs, but a twist cannot sustain the interest prior to it.
The movies "Infernal Affairs", "The departed", "Face/Off" only work because you know the backgrounds of the protagonists. Also I want to play on the symmetry between the two brothers lives.
They fight for what they believe. They lied, killed people. They alienated members of their family. Their wives is in the dark on their real purpose. Their bosses are ruthless men who exploit them for their own advantage.

For me, the most interesting part of a character's action is not the choices he makes, but HOW he comes to make those choices, the thought process, the pro and cons he has to weigh. I am interested in characters who are on the torture rack for most of the film. Who, scene after scene, face increasingly difficult moral dilemmas and ambiguities, who have to make increasingly tough choices.

In the case of your protagonist it seems to be a no-brainer; thanks to his amnesia he doesn't know what he doesn't know. So he's not fully responsible for what he does. Because he's not all there mentally, he's off the torture rack of moral agency and accountability.

Instead, for at least 1/2 the movie, he's acting like a semi-zombie. How exciting is that? The only suspense seems to lie in whether or not he's going to recover his memory in time in order to thwart the attack. And that is beyond his control-- he's at the mercy of the biochemistry of his brain.

I would find the story more compelling, the character more interesting, if he has his full mental faculties at all times. If the terrorists think he has successfully infiltrated the French intelligence and the French Intelligence think he's infiltrated the terrorist cell. If I don't know what to think -- what side he's on. (And maybe he doesn't either.) Until the moment of truth.

That would generate far more suspense in my mind than waiting for the ticking clock to run down. And he either stops being a semi-zombie, regains his full moral agency in time to thwart the attack. Or not.

Others mileage may vary.

fwiw.

It really a story between two brothers.
From the backstory we learn that they were four brothers.
After one was killed by a US drone, one enlisted with the French Secret service to make sure that such bad intel is not repeated. The last two joined a terrorist cell.
One of two terrorists died during the botched assault. The surviving terrorist kidnapped his secret service agent to escape. Because of the memory loss, he is trying to convince him that he also was a terrorist. He tell him that his job was a ruse, he was undercover for them a la departed. The good brother is not entirely convinced, but until the very end we do not know in which direction he will go.

I agree with the anti-amnesiac crowd. It doesn't advance the story. And is it just one brother, or several brothers? You had plural in one of your responses. If it's more than one, then it's interesting to ponder how come he is the odd one out. It's a sibling relationship story and nothing to do with amnesia. makes it more interesting too. Basically interesting idea, just need more thinking - I think. :-)

Yeah - if he's got amnesia, nothing that happens before he gets amnesia can be the catalyst for any events following it ... unless his goal is to figure out why he doesn't remember anything (a la the Bourne franchise).

Still not buying into the amnesia gimmick. If he's amnesiac, how can he know "he must recover his memory before before his brother convinces him to detonate a dirty bomb on US soil"?

A French secret service of Northern African origin is sent to the US to help tracking his terrorist brothers. Concussed and amnesic after a botched assault, he must recover his memory before his brother convinces him to detonate a dirty bomb on US soil.

How has his name been muddied?

Is the goal to regain his memory, or is it to stop his brother from setting off the bomb? Which one ends your story?

To clarify the stakes - specify where the bomb is going to detonate (the more crowded the place the better).

What's the point of the amnesia? How does it contribute to the conflict, the rising tension of the story? It seems gimmicky and unnecessary. There's already an inherent conflict in exploring the Cain vs. Abel relationship --that's the story hook, not the amnesia. And plenty of rising tension can come through the effort to stop the conspiracy (which I presume comes with a ticking clock).

Also, it's the job of an FBI agent (internal to the US) or CIA agent (outside the US) to investigate those kind of conspiracies, so it's not credible that a Secret Service agent would engage in that kind of work.

If he's of Arab origin, has good language skills as well as understanding of the culture and can pass the necessary background check to get the security clearance to work for the Secret Service, then that clearance would also qualify him to work for the CIA, FBI or NSA. And the Federal bureaucrats would give him every inducement to work for one of those agencies where his skills are in rare supply and in such great demand. IOW, from the bureaucracy's pov, he would be squandering his valuable skills in the Secret Service.

What caused his amnesia?
What happened that he has to clear his name?