The bird-cat of Alcatraz

He scratches a count of the days spent in this hell-hole on the prison walls.
He’s made friends with the birds who taunt him with their freedom.
He throws a baseball against the wall of his cell.
Hidden behind a poster of Eartha Kitt is the entrance to the tunnel that he has been digging with a spoon.
There's another tunnel under the vaulting horse. You don’t want to know how he disposes of the earth.
He’s working on a glider.

The interminable agony is only relieved by his outings through the catflap.