Big data-set, probably audiobooks in your language with full transcript. Then fiddling around with your choice of model for training, this might be a good place to start: https://github.com/Kyubyong/tacotron

Just know that the voice will be similar to what Kyubyong or others managed to train meaning it will sound eerily synthetic. Might fit your purposes but it's probably not enough for consumer-applications. Also from what I played around with it optimizing the synthesization is going to be big hurdle if you want it done quickly. Or not I didn't dig that deep into it.