The Enterprise gets stuck in a temporal causality loop when it collides with another ship next to a temporal anomaly. It is forced to repeat the explosion again and again, but each time the loop starts no-one remebers anything from the previous loops except a slight feeling of deja vu. Eventually, having pieced it all together in one loop, they manage to send a message into the next using Data explaining how to avoid the collision. Data interprets the single word "Three" subconciously and the number 3 keeps on appearing wherever he goes, in a Poker game, on computer consoles, everywhere. He realises that it refers to the number of pips on Riker's collar and instead of activating the tractor beam to deflect the other ship's course which was Data's idea, they use Riker's which is to decompress the main shuttlebay, this pushes them clear and they do not start the loop again.
