4x6 - Dragon Ball Z: Dragon Box

No. 20 is cornered by Piccolo, but when Bulma flies by to see how things are going, he attacks her and uses the opening to escape toward his laboratory. Vegeta and the others remaining behind are then told by Trunks and Bulma that No. 20 is actually Doctor Gero and that there are other Artificial Humans besides him. Upon learning this, Vegeta happily takes off in pursuit of Doctor Gero...