***SPOILERS*** Taking in some sun and fresh air in the country private dick Mike Hammer, Darren McGavin, gets involved in a murder that lawyer Arnold Sterling, Neil Hamilton, is accused of by him being in the room with Fraizer Cordey, Robert Riordan, when he was killed. Even though Hammer had his differences with Sterling in court he feels that he's being framed for the murder of millionaire real estate honcho and decides to clear him by tracking down, Mike Hammer style, his killer. It turned out that there was an affair going on between Sterling and Cordey's wife Miram, Allison Hayes, and that with Cordey finding out about it lead to his murder.
With all the evidence pointing against Sterling Hammer, who feels he's innocent, plays it fast and loose in providing him with an alibi in smoking out Cordey's killer. That in finding out the killers escaper plan Hammer gets the almost always fast asleep Barney the Gate-Man, Don Hix, of the Cordey mansion to stay awake long enough to expose who the real killer was in him being the only person who saw him leave right after Cordey was murdered.
***SPOILERS*** It was a long shot on Hammer's part but by getting Barney to go along with his plan the killer not realizing that he was being set up, without a shred of evidence, made a run for it with Hammer hot on his tail. With Cordy's killer slam dunked by Hammer into the lake and admitting his guilt in Cordey's murder the truth came out why he murdered Cordey in the first place. And it all had to do with framing the what turned out to be totally innocent Arnold ,who was also having an affair with that hot cookie Miram Cordey, so he could have the best of both worlds: Get rid of Cordey and frame Sterling for doing it. It was Miram who together with her husbands killer who planned Cordey's murder but screwed up by her exposing, in using a telephone extension, the way she did it which didn't fool the clever Mike Hammer one bit.