Complex sentence: Enders primes a grenade as Whitehorse nods to him, allowing Enders to throw the grenade at him in order to protect the code, and the ensuing explosion kills both Whitehorse and the Japanese captors.
Split into simpler sentences: Enders primes a grenade as Whitehorse nods to him, telling Enders to throw the grenade in order to protect the code. The ensuing explosion kills both Whitehorse and the Japanese captors.