A Tale of 2 Clocks was published in 1962. It is a Trigger Argee adventure, and touches on Quillan, Pilch, plasmoids, and Old Galactics.
This work is essentially a mystery, which Trigger Argee eventually unwinds, somewhat by accident. Trigger is one of two recurring female lead characters for Schmitz. Like Telzey, she is privileged and extremely capable, but unlike Telzey, she has little or no psionic ability. Instead, she is equipped with above average intelligence, training, and a dollop of creativity.
Several of Schmitz' strengths as a writer come out in this yarn. Human perception gets questioned, as the alleged culprits turn out to have a very unexpected nature and motivation. Qualities of "good" and "bad" are played with ironically.
Take Pilch, for example. She is powerful and unrelenting enough to take on a forbidding mien to Trigger and others, but Schmitz makes clear that she is basically benign. She also appears in other works, as does the resourceful free-lance, semi-criminal detective, Quillan.
Not as exciting as some other works, but a thought-provoking and satisfying read nonetheless.