Plot
Collects Optimus Prime (2016 IDW) #15-21.
Darkness falls over Cybertron as the legendary Onyx Prime returns, throwing the planet into chaos! What does this mean for Optimus Prime-and Earth? As Onyx and his comrades sow panic and dissension on Cybertron, Windblade defends an already tense planet against a secret that could shatter it forever, while Soundwave questions a fragile alliance, and Optimus confronts a mystery that goes back millions of years.