All books

Action, Adventure | Thriller, Suspense

The Seventh Plague (Sigma Force #12)

Action, Adventure | Short Stories | Thriller, Suspense

Crash and Burn (Sigma Force #11.5)

Action, Adventure | Thriller, Suspense

The Bone Labyrinth (Sigma Force #11)

Action, Adventure | Short Stories | Thriller, Suspense

The Midnight Watch (Sigma Force #10.5)

Action, Adventure | Thriller, Suspense

The 6th Extinction (Sigma Force #10)

Mystery, Detective | Short Stories | Thriller, Suspense

The Devil's Bones: Cotton Malone vs. Gray Pierce (Sigma Force

Action, Adventure | Thriller, Suspense

The Eye of God (Sigma Force #9)

Action, Adventure | Thriller, Suspense

Bloodline (Sigma Force #8)

Action, Adventure | Short Stories | Thriller, Suspense

Tracker (Sigma Force #7.5)

Action, Adventure | Thriller, Suspense

The Devil Colony (Sigma Force #7)

Action, Adventure | Short Stories | Thriller, Suspense

The Skeleton Key (Sigma Force #6.5)

Action, Adventure | Thriller, Suspense

The Doomsday Key (Sigma Force #6)