The current investigation communicates the characteristics of upper-convected second grade nanofluid thin film flow over a time-dependent stretching sheet with variable thermal conductivity and Cattaneo–Christov double diffusion theory. The mathematical model generates a system of nonlinear partial differential equations (PDEs) for heat, momentum, and mass transfer phenomena. Similarity variables converted the PDEs into nonlinear ordinary differential equations (ODEs). Furthermore, received ODEs are numerically rescued with the built-in program Bvp4c in MATLAB. The impact of physical parameters like second-grade fluid (Formula presented.), unsteadiness parameter (Formula presented.), Prandtl number (Formula presented.), Schmidt number (Formula presented.), variable thermal conductivity (Formula presented.), variable diffusivity (Formula presented.), the square of dimensionless film thickness (Formula presented.), relaxation time (Formula presented.), and retardation time (Formula presented.) are scrutinized. Tables revealed numerical exposure and graphs depict the geometrical aspect of the current study. The velocity field is improved by heightening the λ, magnification in temperature is found for greater conductivity parameter (Formula presented.) Greater (Formula presented.) in the temperature profile goes smaller. The rate of mass transfer diminishes by uplifting the estimations in relaxation time parameter (Formula presented.)