MIKE DEAN has the biggest names in hip-hop in his address book, having produced for Kanye, Travis Scott, Frank Ocean, and Beyoncé. But when the LA hitmaker found himself hunkered down at home during the 2020 coronavirus pandemic, he decided to apply the experience of self-isolation to music of a considerably different character. Digging into his extensive collection of hardware synthesizers, he composed a sprawling, 93-minute foray into space music, more Tangerine Dream than Dark Twisted Fantasy. Assembled almost entirely from one-take sessions improvised live for fans on the internet, 4:20 proceeds like a descent into the deepest recesses of the mind. Pulsing minor-key arpeggios and gradually unfurling envelopes drive the music stealthily forward, casting fleeting glimpses back at Kraftwerk, John Carpenter, and Jan Hammer. The mood begins dreamily in the early passages of “THE FIFTH DAY,” but soon turns dark as overdriven, pitch-bent solos twist ominously through the frame. Drums don’t enter the mix until “THE EIGHTH NIGHT PART 1,” when thudding kicks and blasts of white noise suggest a nightmarish approximation of trap music; in “THE NINTH DAY,” the arps speed up and turn monotone, as though Dean’s confinement had entered a fidgety new phase. All that restless energy boils over in the closing suite, “THE TWELFTH DAY,” four-to-the-floor kicks accelerating beneath gravelly waveforms, tones getting meaner and murkier—until, in the final minute, the tempo slows, and gorgeous chords emerge like the sun peeking from behind dark clouds. Out of desperation comes acceptance, and maybe even something like hope.