A turbine vane of a gas turbine engine, the turbine vane including an airfoil comprising: an airfoil section having an airfoil wall defining a leading end, a trailing end, and first and second sides (68c, 68d) joining the leading end and the trailing end, the first and second sides (68c, 68d) radially spanning in a longitudinal direction between first and second ends (68e, 68f), the airfoil wall circumscribing an internal core cavity; first and second platforms (62, 64) attached, respectively, to the first and second ends (68e, 68f), the second platform attached to the second end including a plenum; and a cooling passage network embedded in the airfoil wall between inner and outer portions (68g, 68h) of the airfoil wall, the cooling passage network having an entrance region adjacent the first end of the airfoil section, a plenum region between the entrance region and the second end of the airfoil section, and an exit region adjacent the plenum region, the entrance region including a plurality of flow guides (84; 84a, 84b, 84c) dividing the entrance region into a plurality of channels (86; 86a, 86b, 86c, 86d) opening into the plenum region, and the plenum region including a plurality of pedestals (88; 88a, 88b, 88c) having a shape different from the flow guides (84; 84a, 84b, 84c, 84c), wherein the cooling passage network has a flow network axis extending in the longitudinal direction which is a radial direction relative to the engine central axis, and wherein an inlet to the entrance region is defined by the first platform and an exit to the exit region is defined by the second platform, such that the inlet and/or exit are aligned laterally relative to the flow network axis either toward the leading end of the airfoil section or toward the trailing end of the airfoil section, wherein the cooling passage network includes an outlet orifice opening to the plenum of the second platform, wherein each of the flow guides (84; 84a, 84b, 84c) has a distinct shape among the plurality of flow guides (84; 84a, 84b, 84c), and characterised in that: the flow guides (84; 84a, 84b, 84c) are grouped such that at least two of the flow guides overlap in a direction perpendicular to the longitudinal direction, wherein two of the flow guides (84a, 84b) have a gentle turning profile to orient the flow to the flow network axis; and the exit region includes a single rib that is elongated in the longitudinal direction from a leading end to a trailing end, and the plenum region extends longitudinally up to the leading end of the rib. an airfoil section having an airfoil wall defining a leading end, a trailing end, and first and second sides (68c, 68d) joining the leading end and the trailing end, the first and second sides (68c, 68d) radially spanning in a longitudinal direction between first and second ends (68e, 68f), the airfoil wall circumscribing an internal core cavity; first and second platforms (62, 64) attached, respectively, to the first and second ends (68e, 68f), the second platform attached to the second end including a plenum; and a cooling passage network embedded in the airfoil wall between inner and outer portions (68g, 68h) of the airfoil wall, the cooling passage network having an entrance region adjacent the first end of the airfoil section, a plenum region between the entrance region and the second end of the airfoil section, and an exit region adjacent the plenum region, the entrance region including a plurality of flow guides (84; 84a, 84b, 84c) dividing the entrance region into a plurality of channels (86; 86a, 86b, 86c, 86d) opening into the plenum region, and the plenum region including a plurality of pedestals (88; 88a, 88b, 88c) having a shape different from the flow guides (84; 84a, 84b, 84c, 84c), wherein the cooling passage network has a flow network axis extending in the longitudinal direction which is a radial direction relative to the engine central axis, and wherein an inlet to the entrance region is defined by the first platform and an exit to the exit region is defined by the second platform, such that the inlet and/or exit are aligned laterally relative to the flow network axis either toward the leading end of the airfoil section or toward the trailing end of the airfoil section, wherein the cooling passage network includes an outlet orifice opening to the plenum of the second platform, wherein each of the flow guides (84; 84a, 84b, 84c) has a distinct shape among the plurality of flow guides (84; 84a, 84b, 84c), and characterised in that: the flow guides (84; 84a, 84b, 84c) are grouped such that at least two of the flow guides overlap in a direction perpendicular to the longitudinal direction, wherein two of the flow guides (84a, 84b) have a gentle turning profile to orient the flow to the flow network axis; and the exit region includes a single rib that is elongated in the longitudinal direction from a leading end to a trailing end, and the plenum region extends longitudinally up to the leading end of the rib. the flow guides (84; 84a, 84b, 84c) are grouped such that at least two of the flow guides overlap in a direction perpendicular to the longitudinal direction, wherein two of the flow guides (84a, 84b) have a gentle turning profile to orient the flow to the flow network axis; and the exit region includes a single rib that is elongated in the longitudinal direction from a leading end to a trailing end, and the plenum region extends longitudinally up to the leading end of the rib.