An impulsive scientist who cuts corners in her research work creates an uncontrollably mutating organism that speeds up the aging process.

When a friend of Mac's is injured in a crash, Mac agrees to test the new racing engine designed by the Phoenix Foundation. However a business rival has other plans for him, and he has someone from the inside to help him.

Penny Parker's big chance in a major professional role is threatened from two directions: a money shortage and several deaths linked to the musical she is set to perform in.