Watson's biohacker friend Hobie (aka the man with the glowing chest) returns when he rushes his new girlfriend to the Holmes Clinic after they partake in a gene-editing experiment that goes wrong. Meanwhile, Watson becomes suspicious of Sherlock.

When a patient arrives at the Holmes Clinic plagued by a mysterious neurological disorder, Watson and the fellows discover they were forced to eat their parents amid a childhood survival incident. Meanwhile, Adam is struggling with how his future will change as a father.