Fantastic Four and Power Pack #2

Stop! Read this! Have you seen these missing children? JACK POWER, brown hair, brown eyes, can expand his density into a cloudy mass or shrink down to a fraction of his size, also answers to ""MASS MASTER."" He is probably with FRANKLIN RICHARDS, blond hair, blue eyes, wearing a t-shirt with a ""4"" on it, also answers to ""SON OF A GENIUS."" They've run away from home together to make careers as solo heroes, and Power Pack has to track them down before KRAVEN THE HUNTER does!

Image: Fantastic Four and Power Pack #2 - Marvel Comics

Fantastic Four and Power Pack #2