a=Plot3D[{0,Sin[x] Cos[y]},{x,0,π/2},{y,0,π/2},Mesh->False,PlotStyle->{{Opacity[0.2],Red},{Opacity[0.2],LightBlue}},Filling->{1->{2}},BoundaryStyle->{Thick,Blue}]

α[y_,λ_]={1,y, λ Sin[1]Cos[y]}

b=ParametricPlot3D[α[y,λ],{y,0,π/2},{λ,0,1},Mesh->False,PlotStyle->Opacity[0.4],BoundaryStyle->{Thick,Red}]

Show[a,b]

ParametricPlot3D[α[y,λ],{y,0,π/2},{λ,0,1},PlotStyle->Opacity[0.4],BoundaryStyle->{Thick,Red}]