This is the fifth book of the Iron Warriors 1 series. a preview is shown below.
After still being unable to defeat the leader of the Fire Resistance, Anthony returns to the base defeated once again. This time, Dan was in the area. when the two met, they went inside to restore the headquarters. After restoring the headquarters, Anthony suggested that they put their prototype armors, the Buster MKI armor, through upgrades. After upgrading the armor, Anthony went out back to battle. Becoming defeated for the third time in a row, Anthony called for backup. All of the members of The Armored Fire appeared, Evan reporting that Dan turned in sick. Anthony was confused at this, for Dan never came into battle. After finding the Fire Resistance leader, the battle began once again...