Borders of Infinity by Lois McMaster Bujold is a collection of 3 previously published novellas: Mountains of Mourning, Labyrinth, and The Borders of Infinity. All 3 feature Bujold's hero Miles Vorkosigan, the handicapped royal soldier from the planet Barayar.

In Mountains of Mourning, Miles travels to the back country of Barayar to investigate the murder of a baby, who was killed because she was born with a cleft pallet.

In Labyrinth, Miles attempts to recruit a geneticist to the Barayaran cause, but ends up bonding with a genetically-engineered female super soldier.

In The Borders of Infinity, Miles is taken prisoner by the Cetagandans. He hopes to rescue a prisoner, but ends up planning a massive prison break.

When I read the first 2 stories, I was optimistic that they would be joined by a common theme - Miles's protection of others who were punished for being handicapped at birth. But the third story did not continue this theme. So, the 3 stories are tied together only by a brief narration in which Miles relates his activity to a superior officer.

As a result, this is little more than an omnibus of loosely related stories, each of which is good, but not great.