First Alien Contact: First Interstellar War

Humans have been in space four hundred years without finding a higher civilization.

They send a super dreadnought out to search. Four hundred and fifty-two light-years from Earth, they find a cluster of space-faring species and the first one they meet fires on them. The humans find themselves embroiled in the middle of a war. It's a war of good vs evil. The humans can't chance the monsters following them back to Earth and commit to a fight they must win.