A moment after the scanning crew went into the ship, a loud thump was heard and then a call from inside for assistance. TK-421 and TK-422 then went inside and were quickly stunned by Han Solo's blaster. Luke Skywalker then put on his armor and masqueraded as his until rescuing Leia Organa.
Later, their unconscious bodies were found along with the scanning crew and taken to the medical bay. TK-421 was flirting with Imperial Nurse Grumblemeyer when Luke Skywalker and his cronies showed up during the Battle Of Yavin. TK-421 was killed when the Death Star blew up.
TK-421 is the only Stormtrooper named in the trilogy.