A trade paperback collecting Y: The Last Man #18-23.
Now more than halfway across the country, Earth's sole surviving human male, Yorick Brown, and his companions, cloning specialist Dr. Allison Mann and government agent 355, are preparing for the final leg of their journey to San Francisco, where Dr. Mann's most important experiment awaits. But before they can leave, they need to get antibiotics for the planet's only other living male - Yorick's monkey, Ampersand. For Yorick, that means an enforced stay in the back country of Colorado with one of 355's former associates, the retired agent 711.
But Yorick is in for much more than a quiet weekend in the woods. Of all the dangers that he's faced in his travels, what awaits him in 711's small cabin will be the hardest to confront = and will also prove to be the difference between life and death for the world's last man.
This volume collects two story arcs: "Safeword" (#18-20) and "Widow's Pass" (#21-23).