The Tome Of Forbidden Power

It is the year 2017 and the world is moving as it always has, at least to most people. A group of individuals has been brought together by the design of a single man. He has given them a grave task. A secret and ancient knowledge has been discovered by someone who would abuse its power. This is the knowledge of magic. A secret long buried by those too terrified of its potential for destruction or those wanting to use it for themselves. This has allowed the wielder of this knowledge to summon beings from other planes of existence into our own, at various points in time through history. The party of heroes has been given access to the ability to travel through time to find these otherworldly beings and send them back, or destroy them entirely.