A configuration of seals disposed around and between a plurality of ring segments (10) arrayed annularly about the periphery of moving blades in a gas turbine engine. The seals function to retain coolant in the plenum (18) within each of the ring segments (10). The seals are disposed atop a substrate (16A), which forms the top of the plenum (18). The first seal (25) is made of a piece of sheet material and seals the gap between adjacent ring segments. This seal has an edge (25A) thereof creased for mating with a similar seal on an adjacent ring segment. A second seal (27), which is also made of sheet material, seals the ends of the plenum (18) of the ring segments (10). Lastly, a third seal (29), which is also made of a piece of sheet material, seals the sides of the second seal (27).