Dashiell Hammett has developed a novel technique for rounding out his mystery stories. Whenever he finds himself involved in a maze of plot difficulties, he blithely adds another character, whom nobody else in the story knows anything about, and proceeds merrily on his way.

The early Thin Man pictures suffered from Mr. Hammett's obvious failure to learn what English A students accept as gospel, but they were made enjoyable and often very amusing by some clever dialogue and by a pair of Hollywood's best wise-crackers. In the latest of the series, "The Shadow of the Thin Man," the former redeeming feature has been scrubbed away to the bone, and nothing is left but Mr. Hammett's amazingly naked dramatic structure. William Powell, as detective Nick Charles, still finds great sport in solving murders while sipping highballs' surprisingly enough, no criminal has yet thought of swiping his cocktail shaker and thus eliminating Charles as God's gift to law and order.

Myrna Loy blinks sweetly through hell and high water, and if she isn't completely oblivious to what's going on, she is well on her way. Asta, the poor man's Rin-Tin-Tin, is back again, but to most moviegoers his cute trick of looking for stray fire-hydrants is about as worn out as the hydrants must be by this time.

"Naval Academy," with Freddy Bartholomew, is the second feature on the bill.