Abstract: An enclosed mousetrap (10) has a trap mechanism (12) mounted on a back wall member (26) and having a bail wire (36) with a straight portion (42) that engages a downwardly projecting detent projection (66) of a catching member (58) in a line contact relationship to ensure effective operation of the enclosed mousetrap. The detent projection (66) is preferably stamped from sheet metal to include a lower surface (102) defined by a front ramp portion (104), a rear detent portion (106), and a lower curved portion (108) that extends between the ramp portion and the detent portion. The lower detent surface (102) preferably has a constantly increasing width in a rearward direction to provide the greatest length of line contact with the bail wire portion (42) in the cocked position to thereby provide frictional capability in holding the trap mechanism cocked.