Porthos catches an alien pathogen, and Archer waits anxiously in sickbay while trying to repair relations with the offended Kreetassans.
Archer, T'Pol, Hoshi Sato and Porthos return from five days on Kreetassa, where the captain has been trying to smooth over a diplomatic offense, only to learn the beagle has picked up an alien pathogen. Enterprise needs a plasma injector from the Kreetassans, but talks collapse when they learn Porthos urinated on a sacred tree, and Archer bristles at the conditions they set for an apology.
Archer spends the night in sickbay watching Phlox work and worrying about his dog, while dreams of Porthos's funeral and his unspoken tension with T'Pol keep him from rest. Phlox offers frank advice, and T'Pol urges him to make amends. Porthos recovers after a pituitary transplant from an alien chameleon, and Archer performs the elaborate Kreetassan ritual, cutting and arranging wood and chanting, which earns the parts. Rick Berman and Brannon Braga wrote this second-season comedy, directed by David Straiton, which reveals Porthos was the last of a litter Archer nicknamed the Four Musketeers.