"Sir Reginald Styles" is about to convene a conference that could finally deliver world peace when he is the victim of an assassination attempt. This attracts the attention of UNIT and so the "Brigadier" (Nicholas Courtney) drafts in the help of the "Doctor" (Jon Pertwee) and "Jo" (Katy Manning) to investigate a strange glowing device. It turns out that this is some sort of a portal to the future from which someone is sending heavily armed guerrillas. Why, though? Well pretty quickly we discover that it's the eponymous antagonist of the "Doctor" who are determined that their empire shall not be compromised by the meddling of their pesky foe. As the cat and mouse game ebbs and flows, the "Doctor" has to deal with not just his old enemy, but their henchmen the "Ogron" (an early "Klingon"?) and the manipulative "Controller" (Aubrey Woods). This is more my kind of adventure with plenty of action, a good solid story and someone has had great fun developing some visual effects for the lasers and the disintegration gun. There's loads of early evening menace and though I could have done with a few more "Dalek" encounters, it's still an entertaining four-part series that condenses the story tightly with a focus on a dastardly plot that mixes timelines, locations, and might just stop WWIII.