Complex sentence: The three put aside their mounting personal conflicts and drive a truckload of explosives to the installation, only to be stopped at the perimeter when Zac detects dangerously high levels of ionising radiation that could prematurely set off the explosives.
Split into simpler sentences: The three put aside their mounting personal conflicts and pickup a truckload of explosives to the installation. Proceeding to the perimeter of the installation, they must stop when Zac detects dangerously high levels of ionising radiation that could prematurely set off the explosives.