Yes, a B grade Film Noir with lots of bad acting from most involved,
BUT not from all, the co-director and actor Edmond O'Brien
is very good as
the corrupted and turned rotten Police detective Lieutenant Barney Nolan,
and also the legendary Carolyn Jones (the classic Morticia Addams in
The Addams family TV series in the 1960's) is fine in a minor role as
a bar woman.
This film is based on a novel by the great crime author
William P. McGivern (see more at the top of my Film Noir & Pulp
Fiction page for some more
information about him) the author of many novels later made into hard-hitting
Film Noir films as The Big Heat and Odds against Tomorrow

Shield for Murder, 1951
his 4th novel in a 1952 Pocket Book 1st edition with Cover art by George
Mayers
Cop Barney Nolan has turned a bad egg in the force and
all his colleague's at the station seem to dislike him intensely. Edmond
O' Brien
portrays Barney as someone who couldn't care less, with a smug smile
and a swagger. He's a cold-blooded killer, and we know this as
we've seen him murdering a bookie underling and robbing him of his money,
25 000 USD, already in the intro of the movie.
Barney and the Bar Girl
Barney has a much younger girlfriend, Patty, who works
at a night club and Barney needs money to buy her stuff, as a new house.
John Agar plays - and very BAD at that, the younger cop Mark Brewster
who investigates the murder, but he's the Buddy of old
Barney and has learnt everything from him, so he wouldn't suspect Barney
Nolan would he?
An even worse actor than John Agar, Marla English (Patty)
or the Station boss, Captain Gunnarson (Emile Meyer) is the old fart
playing
the police reporter, who constantly hang around the policemen and rants
about bad corrupt cops, he really stinks, annoying as hell.
But, Edmond O'Brien is great and this film really starts to gear up
during the second half, when Barney gets desperate and he's cornered
with the noose tightening around him. The film has a somewhat surprising
ending with a chaotic shoot-out in a gymnasium full of people.
This Spanish DVD is presented in a 4:3 fullscreen original
ratio in glorious black & white and with an english audio 2.0