Here is a quick rundown (from Wikipedia) of the story that this version of Darth Maul is from:
Old Wounds
The opening story, "Old Wounds" by Aaron McBride, is set in "the third year Imperial Occupation" and begins with Owen Lars trying to teach new words to a toddler-age Luke Skywalker. They see a strange figure on the horizon running towards the Lars homestead, and Owen instructs his wife Beru to bring him his rifle and take the boy inside. The figure dodges warning shots with ease and uses the Force to disarm Owen before smashing the weapon over his head. Standing on triple-jointed droid legs and concealed by a dark hood, the figure calls out through the Force to an unseen enemy. The voice claims to have been tracking this adversary for years, just missing him by two days on Kamino one day on Geonosis and only a few minutes on Mustafar. He had then killed witnesses on Polis Massa before finally gaining crucial information on Mos Espa from an aged Watto, whom he beheads for his greed. The creature declares that he knows threatening Luke would bring his adversary out into the open, to which the hidden voice finally asks through the Force, "Does Palpatine know?" The cyborg-legged monster replies, "No. There is no Palpatine. No Empire. No Jedi. There is no Light. No Dark... Just you and I here now." At this point, Obi-Wan Kenobi bursts out from the sand. The dark figure casts off his hood and reveals himself to be Darth Maul, his severed lower body replaced by a pair of large cybernetic legs and abdomen, and his cranial horns having grown, crown-like, to over three times their original length. Kenobi and Maul engage in furious combat, in which Maul loses a further arm and four horns before being held at Kenobi's mercy. With his lightsaber hilt to Maul's forehead and his finger on the blade-ignition button, Kenobi hesitates to execute his helpless opponent, but has the decision taken out of his hands when the revived Owen blows the former Sith's head apart with his damaged rifle.
Star Wars: Visionaries is a 2005 collection of 11 stories written and drawn by concept artists who worked on the film Star Wars Episode III: Revenge of the Sith. The book is published by Dark Horse Comics and edited by Jeremy Barlow.