An entire town wakes up with dissociative amnesia and is told to be a part of a voluntary social experiment; when one member of the town begins to suspect they are being held against their will, he launches a secret investigation to rediscover his past.

They can’t be “told” to be part of a “voluntary” social experiment. It’s a contradiction.

Why is only one member of the town investigating? Surely everyone in town would want to know what was going on?

Personally, I think you could just go with “When an entire town wakes up with amnesia, the local sheriff must figure out the cause before the community is torn apart.” Or similar – this isn’t perfect at all. It could still be a social experiment, but we don’t need to know that yet. The best thing about amnesia is that the audience discovers stuff at the same time as the characters and by having a few key characters rediscovering themselves you have the opportunity for the audience to connect some dots first – that’s always fun!

I think this would work great as a series.

Hope this helps.