A retractable truck bed cover having an array of parallel aluminum slats joined together by connective hinges including leading and trailing edge configuration for improving the security of the cover by covering and concealing the seam between adjacent slats while improving the connective hinge's resistance to the effects of aging and/or exposure to temperature fluctuations. The truck bed cover connective hinge slat is designed to be in an array of discrete slats, which are joined to one another by means of joiner members secured at each end to slat end caps. The distal ends of the joiner members are attached to slat end caps at the distal ends of the slats, thereby preventing the joiner members from shrinking in relationship to the slats due to aging and/or exposure to temperature fluctuations.