  We use top-down holography to study the thermodynamics of a one-parameter
family of three-dimensional, strongly coupled Yang-Mills-Chern-Simons theories
with M-theory duals. For generic values of the parameter, the theories exhibit
a mass gap but no confinement, meaning no linear quark-antiquark potential. For
two specific values of the parameter they flow to an infrared fixed point or to
a confining vacuum, respectively. As in the Klebanov-Strassler solution, on the
gravity side the mass gap is generated by the smooth collapse to zero size of a
cycle in the internal geometry. We uncover a rich phase diagram with thermal
phase transitions of first and second order, a triple point and a critical
point.
