Return stage (RTC) for throughflow by means of a process fluid along a throughflow direction of a radial turbomachine (RTM), in particular radial turbocompressor return stage (RCC), wherein the return stage (RTC) extends about an axis (X) in a ring-shaped manner, wherein the return stage (RTC) is defined radially inwardly by an inner delimiting contour (IDC) and radially outwardly by an outer delimiting contour (ODC), wherein the return stage (RTC) extends radially outwardly in a first section (SG1) along a first throughflow direction (FD1), wherein the return stage (RTC) extends, in a manner describing an arcuate deflection, radially inwardly from radially outside along the first throughflow direction (FD1) in a second section (SG2), wherein the return stage (RTC) extends radially inwardly from radially outside along the first throughflow direction (FD1) in a third section (SG3), wherein the return stage (RTC) extends, in a manner describing an arcuate deflection, axially from radially inside along the first throughflow direction (FD1) in a fourth section (SG4), wherein at least one guide vane stage (VST) comprising guide vanes (VNS) extends at least along a part of the third section (SG3) and, in the circumferential direction, segments the return stage into flow channels, wherein in each case a profile midline (PML) of a profile cross section (PRC) of the guide vanes (VNS) of the guide vane stage (VST) defines an inner track (ITR) on the side of the inner delimiting contour (IDC) and an outer track (OTR) on the side of the outer delimiting contour (ODC), wherein the progressions of the inner track (ITR) and outer track (OTR) are able to be defined as: θ L = F θ L R L = F R L , with θ: circumferential position angle in a direction of rotation of the radial turbomachine (RTM), with the vertex on an axis (X), L: profile midline path coordinate along the first throughflow direction (FD1) along a mid-height of the respective guide vane (VNS), normalized to a total length of 1, F θ (L): functional relationship between circumferential position angle θ and position L on the profile midline, R: radius of the position of the inner track (ITR) or outer track (OTR), wherein the guide vanes (VNS) have three successive profile sections (PS) along the first throughflow direction (FD1): a first profile section (PS1), a second profile section (PS2), a third profile section (PS3), characterized in that , in each case for values of L in the profile sections, it holds that: in the first profile section (PS1): θ OTR L ≠ θ ITR L and θ OTR L − θ ITR L ′ ≠ 0 , in the second profile section (PS2): θ OTR L = θ ITR L and θ OTR L − θ ITR L ′ = 0 , in the third profile section (PS3): θ OTR L ≠ θ ITR L und θ OTR L − θ ITR L ′ ≠ 0 . θ: circumferential position angle in a direction of rotation of the radial turbomachine (RTM), with the vertex on an axis (X), L: profile midline path coordinate along the first throughflow direction (FD1) along a mid-height of the respective guide vane (VNS), normalized to a total length of 1, F θ (L): functional relationship between circumferential position angle θ and position L on the profile midline, R: radius of the position of the inner track (ITR) or outer track (OTR), a first profile section (PS1), a second profile section (PS2), a third profile section (PS3), in the first profile section (PS1): θ OTR L ≠ θ ITR L and θ OTR L − θ ITR L ′ ≠ 0 , in the second profile section (PS2): θ OTR L = θ ITR L and θ OTR L − θ ITR L ′ = 0 , in the third profile section (PS3): θ OTR L ≠ θ ITR L und θ OTR L − θ ITR L ′ ≠ 0 . <EOS>