Zeno, a notorious gunfighter that bears an uncanny resemblance to Dr. Smith (Johnathon Harris in a dual role) is chased to the Robinson's adopted world by space marshal Claudius (60's TV fixture and voice impresario Allan Melvin) and ends up (of course) switching places with the cowardly, gun-shy doctor. This is a strictly comic, bare-bones episode with a lot of campy humour, silly-looking props (notably the flying jail), minimalist sets, and a ridiculous premise: no explanation is offered as to why Zeno ends up on the planet within yards of his exact double, why the Robinsons are so credulous (despite having encountered duplicate Smiths before) or why Smith couldn't simply recount one of his various adventures with Will when he wanted to convince the young Robinson that he was the real thing. On the plus side, Harris manages to produce a credible 'alternate' voice for tough-guy Xeno. By now the show was highly influenced by the high-camp stylings of mega-hit 'Batman' (1966) but at least there was some cleverness and sly-wit underlying the Dynamic Duo's preposterous adventures - 'Lost in Space' was just becoming contrived, repetitive, silly, and sloppily written.