Vesper Four, also known as The Scientist, is a member of the Vesper Council of Six. Vesper Four is responsible for developing surveillance equipment and weapons. The most recent Vesper Four was Sandy Bancroft.
- Ian Kabra (on the card as Suspect Unknown)
- Develops surveillance technology.
- Builds the Vesper arsenals.
- Keeps tabs on the Vesper targets.
Engineering expertise, imagination and an appetite for destruction, and also loves to blow things up.
- He appears as a weatherman or a meterologist as "Sandy the Breeze" Bancroft reporting in front of Mount Vesuvius, Pompeii.
- He messages a text to Vesper One asking for further instructions.
- His main objective was to keep tabs on Hamilton Holt, Jonah Wizard, and Erasmus Yilmaz.
- He along with Vesper Two, Vesper Six plan to overthrow Vesper One.
- He fakes sleeping and reports the Wyomings' treason to Vesper One].
- He is beaten up by the hostages after the truck escape fiasco.
- He plans to flood Chicago, Illinois using the Machina Fini Mundi.
- He is promoted to Vesper Two by Vesper One.
- He along with Vesper One hands out stone batons to the vespers as their weapons were sucked by the electromagnetic field of the Machina Fini Mundi.
- He is then, arrested by the police along with the Wyomings.
- He is the least appeared Vesper in the Cahills vs Vespers series who is a member of the Council Of Six.
- He appears the least in the books, as V-1 is always mentioned.
- He changes sides suddenly, first to Isabel and then to Damien.