Sonia and Marco are ambulance drivers, in France. A virus is raging across the countryside which is transforming humans into a sort of animalistic zombie. But these are more of the type of "Zombies" we've seen in 28 DAYS LATER, not the undead.
First, the couple has to get away from an overzealous army woman, then they take refuge in an old deserted building. But Marco has been bitten and it's only a matter of time before he begins to mutant. Sonia cares for him as long as she can and is forced to lock him in one of the rooms once he tries to attack her. This is when a group of survivors crashes the place--and they are not exactly friendly humans.
The entire movie takes place against a winter backdrop, which provides some interesting visuals, and it's an intense survival tale, like 30 DAYS OF NIGHT. MUTANTS is one of the better "zombie" movies I've seen in years.