In it a scientist makes a robot to look after his dying mother, and so the robot doesn't tell the mother stright out that she'll be dead in a week he programs it to lie. So after annoying a lot of people (Astro having to save him) the scientist decides to reprogram the robot. He asks him if the equipment is ready the robot replies with a yes, of cause lying the lab setts on fire and the scientist sends the robot (now not able to lie) to get help. When the people hear what he has to say they get really angre and distroy him
, and Astro buts out the fire. After this Astro and the scientist are at the mothers death bed. She asks where the nice robot that looked after her is and (She had poor eyes) Astro says "Here I am ma". With the mother dead the scientist says "I thought you said you couldn't lie?" to which Astro replies "I little white lie never hurt any one"!!!!!!!!! 
It's REALLY sad. Kinda like the boy that called wolf.
(Sorry about the long post)
but I do recall the similar story in the 1980 anime. 
