S2, E9: Will (Eric McCormack), Karen (Megan Mullally) and Jack (Sean Hayes) unknowingly take a hallucinogenic drug, which causes Will and Jack to wonder if they're each other's soul mate and has Karen giving her last "performance" as Mrs. Stanley Walker. Meanwhile, Grace (Debra Messing) is shocked when her high-powered client (guest star Chelsea Handler) takes up with her sister Janet (guest star Mary McCormack).