To start, Robert tries to touch--literally touch--the tumor that killed President Ulysses S. Grant. But will its keepers (Dr. Adrianne Noe and Brian Spatola) let him?

Next, writer David Quammen explains an unsettling discovery in Tasmania. When wildlife photographer Christo Baars noticed strange lumps on the Tasmanian Devils he was photographing, scientists jumped in to figure out what was going on. Dr. Anne-Marie Pearse found a shocking answer--the lumps were infectious tumors, and they were leaping between Devils.

How could this happen? Jad and Robert talk to cancer biologist Carlo Maley about the improbable sequence of events that allowed the tumors to take flight.