"Threshold"
UK Tape 2.6 - Episode 1

Lieutenant Paris makes history by becoming the first person to make a transwarp flight. But, soon after his shuttle returns from Warp Ten, he undergoes startling biochemistry changes. His cell membranes begin to degrade and, despite the Doctor's best efforts, Paris dies. Hours after the pronouncement of death, Paris is discovered breathing, his body going through accelerated mutations which leave him radically transformed into a bizarre and terrifying cross between a human and amphibian.

"Meld"
UK Tape 2.6 - Episode 2

When a crew member is murdered, Tuvok's investigation leads to another crewman, Ensign Suder, who finally admits he is the perpetrator. Vulcan instincts prohibit Tuvok from determining a logical motive for committing such a crime, so he attempts to understand the violent impulses of a criminal by performing a mind-meld on Suder -- with deadly results.