Murder-mystery writer Cornelia van Gorder [Agnes Moorehead] has leased a large countryhouse called "The Oaks". After being in the house for only a few days,Cornelia's longtime maid, Lizzie Allen [Lenita Lane], informs her that the servants areupset over rumors they have heard about the murders committed in the houselast winter by the archcriminal who goes by the name of The Bat. They fearhe is back, and they're also concerned about rabid bats that havesupposedly been released by The Bat. That's hysterical nonsense, Corneliasays as she heads into Zenith to conduct some business at the Zenith Citybank. She has another surprise when vice-president and head cashier of thebank, Victor Bailey [Mike Steele], mentions that the bank president and owner of TheOaks, John Fleming [Harvey Stephens], once said that he would never rent the house. Again,Cornelia is not concerned since she rented the house from his nephew, MarkFleming [John Bryant].As Cornelia chats with Victor's wife Dale [Elaine Edwards] and Lieutenant "Andy"Anderson [Gavin Gordon],a detective with the Zenith City Police Department and a memberof the board of directors of the Zenith Bank, Victor is informed that thebank has been looted of over $1,000,000 in bonds and negotiablesecurities. Since the only two people with access to the vault are Victorhimself and bank president John Fleming, who is currently away on ahunting trip in the Northwoods, Victor is arrested and attempts are madeto contact Fleming.Meanwhile, at his lodge in the Northwoods, John Fleming informs hishunting partner and physician, Doctor Malcolm Wells [Vincent Price], that he has justembezzled over $1,000,000 from the bank and he needs help in covering itup. His plan is to murder their hunting guide and disfigure the bodyenough that Wells can pass it off as Fleming. After "Fleming" is declareddead and buried, the two of them will split the million. The money iscurrently hidden in the Fleming family crypt in Zenith, he explains. Wellsrecalls a time, however, when Fleming was very sick and, in fever, talkedabout hiding the money in a hidden room in The Oaks. When Flemingannounces that, if Wells doesn't go for the deal, he'll kill Wells andcall it a "hunting accident," Wells turns his shotgun on Fleming.I ain't afraid of ghosts, Lizzie tells Cornelia when they read in thepaper of John Fleming's death. Although the rest of the staff, except forWarner [John Sutton], the chauffeur, have quit their jobs, Lizzie intends to stay with"Miss Corny" under any circumstances. Because there's a storm brewing,Lizzie and Cornelia check to be sure all the doors and windows are shut.Lizzie suddenly sees a black-clawed hand reach through the front door,just about to grab Cornelia's throat. Lizzie's screams scare him off;Cornelia calls the police. They send someone over to check the grounds,but no one is found.Cornelia and Lizzie go upstairs and lock themselves in a bedroom.Meanwhile, The Bat has cut a hole in the front-door window, unlocked thedoor, and entered the house. As Cornelia and Lizzie try to sleep, he opensthe transom into their room and releases a bat that flits around for amoment, lands on Lizzie's arm, and bites her. Concerned that the bat maybe rabid, Cornelia phones Dr Wells. He's in his laboratory conducting anexperiment (on a bat!), but he comes over to look at Lizzie. He dressesher arm and gives her a sleeping pill. After examining the bat, heproclaims that it doesn't look sick but that he won't know for sure untilhe examines its brain under a microscope. Meanwhile, Lt Andy has takenadvantage of Dr Wells' absence and let himself into the lab where hesnoops around and notices the experimental bat and a figure of a large batin one of the windows. Andy then drives over to The Oaks, arriving just asWells is leaving. Andy points out the hole in the glass where The Batgained entrance and assures Cornelia that an officer will keep watch onthe house for the rest of the night.Several days/weeks? have gone by, and Victor Bailey's trial is comingup. His secretary, Judy Hollister [Darla Hood], apparently has some information thatwill help to acquit him, so people are beginning to suspect that JohnFleming robbed his own bank. Lt Anderson, concerned that his holdings atthe bank will be wiped out if the money isn't found, pays a visit to MarkFleming. Mark reveals that he hasn't received a dime of his inheritancefrom his uncle because the money is nowhere to be found. Meanwhile,Cornelia has managed to retain John Fleming's old maid, Jane Patterson [Riza Royce].When Dr Wells, Dale Bailey, and Judy Hollister drop by for tea, they alldiscuss the possibility that it was John Fleming who actually robbed thebank. Cornelia suggests that Fleming may have hidden the money in TheOaks, and Dale phones Mark to see whether there are any floorplans of thehouse. Mark isn't sure why she would want the floorplan, so Lt Andysuggests that maybe Uncle John DID steal the money and hid it in thehouse. Mark agrees to come over that evening and help look for the plans.Come over Mark does, but he lets himself into the house with his ownkey while Cornelia, Dale, and Judy are eating dinner. He moves aside agrandfather clock and opens a panel to a secret closet. While he looksover the floorplans, The Bat enters the house and sneaks up behind,clobbers Mark, and makes off with the floorplans. After dinner, Corneliais amazed to hear the grandfather clock striking the hour, when it hasn'tdone so in years. They notice that the clock has been moved, then Dalesees the panel behind it. They open the panel to find Mark Fleming...dead.Lt Anderson and Dr Wells are notified after the police are called. Afterseeing the claw marks on Mark's throat, Anderson proclaims it the work ofThe Bat.Later that night, after the police have combed the house for cluesand Mark's body has been taken to the morgue, Lt Anderson remains to makesure all the windows and doors are locked. As he checks the rooms, hedoesn't notice that Warner is watching him. After the ladies have gone tosleep, Cornelia and Lizzie in one room, Judy and Dale in another, The Batcomes in through the unlocked front door. First, he cuts the phone line.He then goes up to the third floor and into a storage room where he startstapping on the walls. The noise wakes up Judy and Dale. Thinking she maybe able to find the hidden money and clear her husband, Dale sneaks up tothe third floor. The Bat locks her in the room and runs downstairs. On theway down, he runs into Judy and kills her, then he flees out the frontdoor, after first being struck in the neck by a poker thrown by Cornelia.Shortly thereafter, Lt Andy comes in the front door. He explains thathe was chasing someone on the grounds and asks as to the whereabouts ofWarner the chauffeur. Warner suddenly comes in the front door and explainsthat he was following Anderson when he was suddenly hit on the head. It'sthen that Anderson remembers seeing a wanted poster with Warner's pictureon it, but Warner says that he was tried and acquitted. He vehementlydenies being The Bat. Suddenly, Dr Wells walks in the front door. He hadan accident about a mile down the road, he says, and walked back to thehouse to use the phone. Andy notices blood on Wells' neck. Hmmm, could DrWells be The Bat?Several nights later, after the house had been searched from top tobottom without finding any money or a hidden room, Cornelia decides toconduct an investigation of her own. When the detective on duty fallsasleep in his chair, Cornelia goes up to the third floor to look around inthe storage room where The Bat was tapping on the walls. Measuring thedistance between the storage room and the room next to it, Cornelianotices a loss of about five feet between the two rooms. She pounds on thewalls, then on the panels of a fireplace. Suddenly, one of the panelsopens up, revealing a switch that allows the fireplace to swing open.Cornelia has found the hidden room. It is empty, except for a safe in thewall. As she kneels before the safe, the fireplace swings closed, trappingher in the room.Meanwhile, The Bat has gone to Dr Wells' lab where he hangs a note onthe wall. It says: "Here lies The Bat -- threatened with exposure hedestroyed himself." As The Bat turns around, Wells walks into the room withhis gun drawn. The doctor taunts The Bat with the fact that he knows wherethe money is hidden and that he's going to shoot The Bat and put his ownsign on his own chest. Just as Wells cocks the gun, The Bat leaps at him.They struggle, the gun goes off, and it is Wells who is shot.Cornelia's pounding on the walls wakes Lizzie, who notices thatCornelia's bed is empty. She goes down to the parlor and tries to wake upDetective Davenport [Robert Williams], only to find him drugged into sleep. Lizzie wakesthe maid who goes to get Warner, only to find him missing. The detectivecalls headquarters to alert Lt Anderson only to find that he's been sentto investigate the death of Dr Wells. The three of them -- Lizzie, Jane,and Davenport -- look outside for Cornelia, but she doesn't answer theircalls. Suddenly, Lizzie notices a light on the third floor and redirectseveryone up there. The air in the hidden room is rapidly depleting.Cornelia can barely manage call out. She tells them to hit the panels overthe fireplace and then passes out. Lizzie gives each panel a pound, findsthe switch, and opens the fireplace just in the nick of time.Outside the house, The Bat is slinking around in the bushes. He hasstarted the garage on fire, but Cornelia is wise to him. That fire was setto get us out of the house, she tells everyone. Instead of leaving, theyturn out the lights and wait. A few minutes later, The Bat appears. WhenThe Bat enters the hidden room, Davenport fires a shot. But The Bat isquicker and shoots Davenport. He then turns to the ladies who are hidingbehind some boxes. Just as he's about to open fire on the ladies, he isshot from behind. Warner enters the room, his gun smoking. They remove thehood from over the Bat's face to find ... Lt Anderson. [Original synopsis by bj_kuehl]
Output: Question: What is the name used to describe the mysterious murderer in this movie?, Answer: the bat