Transformers: Galaxies (Transformers: Galaxies #10)

"Storm Horizon," Part One! Ultra Magnus, one of the four Great Generals of Cybertron's last war, finds himself far from home and his glory days on a deep space exploratory mission. But when his mentor, Alpha Trion, is reported missing from a nearby world, Magnus must solve a mystery with roots in an even more distant past that reaches from Cybertron to the unknown regions.