From the back of the box:
Sometime, somewhere, someone is changing the future by altering our past. A previously extinct primeval entity is being summoned forward through the barriers of time by a fanatical sect, whose aim is to disrupt the future balance of power.
As sole survivor of the once elite 'time corps' you have been chosen by the federation of law and order to thwart this evil conspiracy.
You are to be transported by molecular disruption to combat the entity as it leaps closer to our destiny.
Unfortunately the locals are not keen on time warriors and evil monsters popping up out of nowhere and they tend to get upset.
Luckily you are carrying an energy conversion kit which, is used correctly, changes ordinary objects into a powerful array of stunningly useful mega-utilities, be careful........... some only last a short while.
Destroying certain hostile characters and objects may leave behind a clue as to the identity of one of the conspirators (symbolised by a jigsaw piece) which must be collected, once exposed the entity will be forced to make an appearance in that time zone in order to destroy you and the evidence, you must weaken the monstrosity and force it to retreat whence it came and continue your task in another era.