this early d. c. fontana episode bravely go where tos never go before to the time of it own creation the late 1960s . another bold frontier for the series ( previously explore and but less interestingly and in squire of gothos ) be cross a tomorrow be yesterday establish the show sense of humor by characteristically poke fun at it own historical context . the original series be never equal in any of it worthy successor in make commentary whether comedic or serious on it own historical context . and though not terribly serious and tomorrow be yesterday be a good example . the plot be fairly complicate and a impossible ( from a scientific perspective ) a most of what pass for science in voyager and enterprise and but the strength of fontana dialog and the performance of the regular crew and the guest star ( roger perry be great in this ) carry it . enterprise and on it way to earth and be catapult back in time by a slingshot effect relate to the gravitational pull of a star and to the late 1960s ( ya and i know and a physic class might have help here and but bear with me ) . the ship enters earth gravitational field partially disabled and in a decaying orbit . they be spot and brand a ufo and and a warplane be send to investigate . the crew must figure out a way to repair the time line and return some unwanted guest to earth without memory of visit the enterprise and and and of course and return to the 23rd century without rip the ship apart . the episode be well write and despite the ridiculous premise and and very nicely act . the cinematography be effective and though the effect be some of the bad in the series and and many of the long range shot of the ship should probably have be cut . kirk engages in one of his good fight scene if youre into that sort of thing . an entertaining episode and and one that establish a trope for the entire franchise engagement with the show own historical context . recommend .