The Mexican is an antique gun that Jerry (Pitt) has to smuggle across the border from Mexico. He has some problems. First, his girlfriend Sam (Roberts) wants him to quit his job with the mob. Second, the mob wants the gun or else Sam will be K-I-L-L-E-D. Third, he doesn't know where the gun is or who he is going to have to steal it from, and lastly (who said life was meant to be simple anyway?) the gun is cursed.
If you liked such road movies as From Dusk Till Dawn set in the Mexican desert, you will enjoy this too. The romance of the 2 leads sparkles, (though we don't see much of Sam, rats) and the human obstacles who intervene in their lives are, well, human.

Mankind has been just about wiped out by a virus. What's left of humanity has left the surface and sealed themselves underground in order to escape it. James Cole (Willis) is some sort of prisoner in this underground world, but is given an opportunity for a pardon when he "volunteers" to do some research for those in charge. This research involves going back in time and trying to find out some way to cure this virus so that humans may return to the surface of Earth. In the past, Cole has encounters with Dr Kathryn Railly (Stowe) and Jeffrey Goines (Pitt) when he is put into a mental institution (for saying he's from the future, of course!). He starts to become uncertain as to whether he is from the future or whether he's mentally divergent (imagines himself to be in another world).
The movie is great. What I find particularly amazing is that here is a movie, with time travel, but without plot holes! Brad Pitt is also superb as the mental patient Cole befriends; he rightfully won the Golden Globe and was nominated for the Oscar. Personally, I also found the music to be another great plus for Twelve Monkeys.