Boone is a Zeon captain operating near the Federation's Belfast base in Ireland. When White Base shows up, he sees his chance and launches a series of attacks against it. During one of these raids, he plants a spy named Miharu Ratokie aboard White Base to feed him intelligence on their destination.
Determined to track them down, Boone pursues White Base across the Atlantic, eventually sneaking onto the ship itself using a stolen civilian plane so he can stay in contact with Miharu. She tips him off that they're headed to South America. Boone relays this to Char and gets cleared to pilot the MAM-07 Grublo—a mobile armor he's itching to use for payback against the Gundam, which has already killed several of his men.
The attack goes forward and Boone takes the fight underwater. The Grublo initially has the upper hand, even managing to clamp one of its claws around the Gundam's leg, but the mobile suit breaks free. The Gundam counterattacks, driving a beam saber straight through the Grublo's cockpit and killing Boone in the process.
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