Okay. Two trains travelling towards each other at the speed of light. So, from one train (let's call it train A), the other is moving towards it at the speed of light. The other train shines a torch. They are both moving at the same speed so they both reach train A at the same time.
From train B (the other train), A is moving towards it at the speed of light. It shines the torch, and the torch is moving faster than the train itself (since the train is stationary from it's own frame of reference). So the light should hit train A before train B does.
Obviously both of these scenarios cannot be true, so what happens from each frame of reference?